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Mauro Carvalho Chehabe53dd082007-09-15 07:38:47 -03001 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
Linus Torvalds1da177e2005-04-16 15:20:36 -07003
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
Randy Dunlapca1eda22009-05-06 16:02:58 -070020Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22can also be entered as
23 log-buf-len=1M print_fatal_signals=1
24
25
Stefan Richtera901ebb2006-04-01 01:43:18 +020026This document may not be entirely up to date and comprehensive. The command
27"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28module. Loadable modules, after being loaded into the running kernel, also
29reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30parameters may be changed at runtime by the command
31"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
32
Stefan Richter6585fa82006-04-01 01:44:30 +020033The parameters listed below are only valid if certain kernel build options were
34enabled and if respective hardware is present. The text in square brackets at
35the beginning of each description states the restrictions within which a
36parameter is applicable:
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38 ACPI ACPI support is enabled.
Chuck Ebbertc99c1082007-07-27 10:46:20 +100039 AGP AGP (Accelerated Graphics Port) is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +020043 AVR32 AVR32 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 AX25 Appropriate AX.25 support is enabled.
Robin Getz0ae53642007-10-09 17:24:49 +080045 BLACKFIN Blackfin architecture is enabled.
Randy Dunlapa9913042005-10-23 12:57:11 -070046 DRM Direct Rendering Management support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -070051 GCOV GCOV profiling is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 HW Appropriate hardware is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 IA-64 IA-64 architecture is enabled.
Mimi Zohar6146f0d2009-02-04 09:06:57 -050054 IMA Integrity measurement architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 IOSCHED More than one I/O scheduler is enabled.
Adrian Bunk41e2e8b2005-07-12 13:58:33 -070056 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 ISAPNP ISA PnP code is enabled.
58 ISDN Appropriate ISDN support is enabled.
59 JOY Appropriate joystick support is enabled.
Andre Przywarafef07aa2009-07-10 14:20:35 +020060 KVM Kernel Virtual Machine support is enabled.
Kristen Carlson Accardi11ef6972006-09-28 11:29:01 -070061 LIBATA Libata driver is enabled
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 LP Printer support is enabled.
63 LOOP Loopback device support is enabled.
64 M68k M68k architecture is enabled.
65 These options have more detailed description inside of
66 Documentation/m68k/kernel-options.txt.
67 MCA MCA bus support is enabled.
68 MDA MDA console support is enabled.
69 MOUSE Appropriate mouse support is enabled.
Matthew Wilcox309e57d2006-03-05 22:33:34 -070070 MSI Message Signaled Interrupts (PCI).
Randy Dunlapc8facbb2007-07-31 00:37:40 -070071 MTD MTD (Memory Technology Device) support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 NET Appropriate network support is enabled.
73 NUMA NUMA support is enabled.
john stultz734efb42006-06-26 00:25:05 -070074 GENERIC_TIME The generic timeofday code is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 NFS Appropriate NFS support is enabled.
76 OSS OSS sound support is enabled.
Randy Dunlapc8facbb2007-07-31 00:37:40 -070077 PV_OPS A paravirtualized kernel is enabled.
78 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 PARISC The PA-RISC architecture is enabled.
80 PCI PCI bus support is enabled.
Randy Dunlap7f785762007-10-05 13:17:58 -070081 PCIE PCI Express support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 PCMCIA The PCMCIA subsystem is enabled.
83 PNP Plug & Play support is enabled.
84 PPC PowerPC architecture is enabled.
85 PPT Parallel port support is enabled.
86 PS2 Appropriate PS/2 support is enabled.
87 RAM RAM disk support is enabled.
James Morris20510f22007-10-16 23:31:32 -070088 ROOTPLUG The example Root Plug LSM is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 S390 S390 architecture is enabled.
90 SCSI Appropriate SCSI support is enabled.
91 A lot of drivers has their options described inside of
92 Documentation/scsi/.
James Morris20510f22007-10-16 23:31:32 -070093 SECURITY Different security models are enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 SELINUX SELinux support is enabled.
95 SERIAL Serial support is enabled.
Paul Mundte523d932007-02-28 18:30:01 +090096 SH SuperH architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 SMP The kernel is an SMP kernel.
98 SPARC Sparc architecture is enabled.
David Brownell77437fd2008-07-23 21:28:33 -070099 SWSUSP Software suspend (hibernation) is enabled.
100 SUSPEND System suspend states are enabled.
Steven Rostedtf38f1d22008-12-16 23:06:40 -0500101 FTRACE Function tracing enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 TS Appropriate touchscreen support is enabled.
Alan Sternd4f373e2008-11-10 14:07:45 -0500103 UMS USB Mass Storage support is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 USB USB support is enabled.
105 USBHID USB Human Interface Device support is enabled.
106 V4L Video For Linux support is enabled.
107 VGA The VGA console has been enabled.
108 VT Virtual terminal support is enabled.
109 WDT Watchdog support is enabled.
110 XT IBM PC/XT MFM hard disk support is enabled.
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700111 X86-32 X86-32, aka i386 architecture is enabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 X86-64 X86-64 architecture is enabled.
113 More X86-64 boot options can be found in
Uwe Hermann71cced62008-10-20 09:32:21 -0700114 Documentation/x86/x86_64/boot-options.txt .
Andi Kleenc0115602008-08-22 09:53:39 +0200115 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116
117In addition, the following text indicates that the option:
118
119 BUGS= Relates to possible processor bugs on the said processor.
120 KNL Is a kernel start-up parameter.
121 BOOT Is a boot loader parameter.
122
123Parameters denoted with BOOT are actually interpreted by the boot
124loader, and have no meaning to the kernel directly.
125Do not modify the syntax of boot loader parameters without extreme
Kyle McMartin954a8b82009-02-19 16:48:14 -0500126need or coordination with <Documentation/x86/boot.txt>.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127
Karsten Weiss55588702007-02-13 13:26:21 +0100128There are also arch-specific kernel-parameters not documented here.
Uwe Hermann71cced62008-10-20 09:32:21 -0700129See for example <Documentation/x86/x86_64/boot-options.txt>.
Karsten Weiss55588702007-02-13 13:26:21 +0100130
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
132a trailing = on the name of any parameter states that that parameter will
133be entered as an environment variable, whereas its absence indicates that
134it will appear as a kernel argument readable via /proc/cmdline by programs
135running once the system is up.
136
jens m. noedler9c4751f2006-09-29 02:00:27 -0700137The number of kernel parameters is not limited, but the length of the
138complete command line (parameters including spaces etc.) is limited to
139a fixed number of characters. This limit depends on the architecture
140and is between 256 and 4096 characters. It is defined in the file
141./include/asm/setup.h as COMMAND_LINE_SIZE.
142
143
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530144 acpi= [HW,ACPI,X86]
Bernhard Walle03d926f2007-03-06 02:29:44 -0800145 Advanced Configuration and Power Interface
Randy Dunlapaf23f572009-02-22 17:05:22 -0800146 Format: { force | off | ht | strict | noirq | rsdt }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 force -- enable ACPI if default was off
148 off -- disable ACPI if default was on
149 noirq -- do not use ACPI for IRQ routing
150 ht -- run only enough ACPI to enable Hyper Threading
Randy Dunlapa9913042005-10-23 12:57:11 -0700151 strict -- Be less tolerant of platforms that are not
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 strictly ACPI specification compliant.
Zhao Yakui237889b2008-12-17 16:55:18 +0800153 rsdt -- prefer RSDT over (default) XSDT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154
Randy Dunlap53471122008-03-12 18:10:51 -0400155 See also Documentation/power/pm.txt, pci=noacpi
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156
Len Browna1fdcc02007-03-11 03:26:14 -0400157 acpi_apic_instance= [ACPI, IOAPIC]
158 Format: <int>
159 2: use 2nd APIC table, if available
160 1,0: use 1st APIC table
Len Brown4e381a42007-03-30 14:16:10 -0400161 default: 0
Len Browna1fdcc02007-03-11 03:26:14 -0400162
Thomas Renningerc3d6de62008-08-01 17:37:55 +0200163 acpi_backlight= [HW,ACPI]
164 acpi_backlight=vendor
165 acpi_backlight=video
166 If set to vendor, prefer vendor specific driver
167 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
168 of the ACPI video.ko driver.
169
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700170 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
171 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 Format: <int>
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700173 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
174 debug output. Bits in debug_layer correspond to a
175 _COMPONENT in an ACPI source file, e.g.,
176 #define _COMPONENT ACPI_PCI_COMPONENT
177 Bits in debug_level correspond to a level in
178 ACPI_DEBUG_PRINT statements, e.g.,
179 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600180 The debug_level mask defaults to "info". See
181 Documentation/acpi/debug.txt for more information about
182 debug layers and levels.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183
Bjorn Helgaase76f4272008-11-13 17:30:13 -0600184 Enable processor driver info messages:
185 acpi.debug_layer=0x20000000
186 Enable PCI/PCI interrupt routing info messages:
187 acpi.debug_layer=0x400000
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700188 Enable AML "Debug" output, i.e., stores to the Debug
189 object while interpreting AML:
190 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700191 Enable all messages related to ACPI hardware:
192 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
Thomas Renninger36eec5e2008-08-11 15:03:20 +0200193
Bjorn Helgaasa0d84a92008-11-07 16:58:05 -0700194 Some values produce so much output that the system is
195 unusable. The "log_buf_len" parameter may be useful
196 if you need to capture more output.
Zhang Ruif9891062007-04-24 13:53:22 +0800197
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700198 acpi_display_output= [HW,ACPI]
199 acpi_display_output=vendor
200 acpi_display_output=video
201 See above.
202
203 acpi_irq_balance [HW,ACPI]
204 ACPI will balance active IRQs
205 default in APIC mode
206
207 acpi_irq_nobalance [HW,ACPI]
208 ACPI will not move active IRQs (default)
209 default in PIC mode
210
211 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
212 Format: <irq>,<irq>...
213
214 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
215 use by PCI
216 Format: <irq>,<irq>...
217
218 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
219
220 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
221 Format: To spoof as Windows 98: ="Microsoft Windows"
222
223 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
224 acpi_osi="string1" # add string1 -- only one string
225 acpi_osi="!string2" # remove built-in string2
226 acpi_osi= # disable all strings
227
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530228 acpi_pm_good [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
232
Randy Dunlap4af94f32009-04-17 18:30:28 -0700233 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
234 Format: { level | edge | high | low }
235
236 acpi_serialize [HW,ACPI] force serialization of AML methods
237
238 acpi_skip_timer_override [HW,ACPI]
239 Recognize and ignore IRQ0/pin2 Interrupt Override.
240 For broken nForce2 BIOS resulting in XT-PIC timer.
241
242 acpi_sleep= [HW,ACPI] Sleep options
243 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
244 old_ordering, s4_nonvs }
245 See Documentation/power/video.txt for information on
246 s3_bios and s3_mode.
247 s3_beep is for debugging; it makes the PC's speaker beep
248 as soon as the kernel's real-mode entry point is called.
249 s4_nohwsig prevents ACPI hardware signature from being
250 used during resume from hibernation.
251 old_ordering causes the ACPI 1.0 ordering of the _PTS
252 control method, with respect to putting devices into
253 low power states, to be enforced (the ACPI 2.0 ordering
254 of _PTS is used by default).
255 s4_nonvs prevents the kernel from saving/restoring the
256 ACPI NVS memory during hibernation.
257
258 acpi_use_timer_override [HW,ACPI]
259 Use timer override. For some broken Nvidia NF5 boards
260 that require a timer override, but don't have HPET
261
Luca Tettamanti7e905602009-03-30 00:01:27 +0200262 acpi_enforce_resources= [ACPI]
263 { strict | lax | no }
264 Check for resource conflicts between native drivers
265 and ACPI OperationRegions (SystemIO and SystemMemory
266 only). IO ports and memory declared in ACPI might be
267 used by the ACPI subsystem in arbitrary AML code and
268 can interfere with legacy drivers.
269 strict (default): access to resources claimed by ACPI
270 is denied; legacy drivers trying to access reserved
271 resources will fail to bind to device using them.
272 lax: access to resources claimed by ACPI is allowed;
273 legacy drivers trying to access reserved resources
274 will bind successfully but a warning message is logged.
275 no: ACPI OperationRegions are not marked as reserved,
276 no further checks are performed.
277
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 ad1848= [HW,OSS]
279 Format: <io>,<irq>,<dma>,<dma2>,<type>
280
Randy Dunlap4af94f32009-04-17 18:30:28 -0700281 add_efi_memmap [EFI; X86] Include EFI memory map in
282 kernel's map of available physical RAM.
283
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 advansys= [HW,SCSI]
285 See header of drivers/scsi/advansys.c.
286
287 advwdt= [HW,WDT] Advantech WDT
288 Format: <iostart>,<iostop>
289
290 aedsp16= [HW,OSS] Audio Excel DSP 16
291 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
292 See also header of sound/oss/aedsp16.c.
Randy Dunlapa9913042005-10-23 12:57:11 -0700293
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700294 agp= [AGP]
295 { off | try_unsupported }
296 off: disable AGP support
297 try_unsupported: try to drive unsupported chipsets
298 (may crash computer or cause data corruption)
299
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 aha152x= [HW,SCSI]
301 See Documentation/scsi/aha152x.txt.
302
303 aha1542= [HW,SCSI]
304 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
305
306 aic7xxx= [HW,SCSI]
307 See Documentation/scsi/aic7xxx.txt.
308
309 aic79xx= [HW,SCSI]
310 See Documentation/scsi/aic79xx.txt.
311
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200312 amd_iommu= [HW,X86-84]
313 Pass parameters to the AMD IOMMU driver in the system.
314 Possible values are:
Joerg Roedel54b4cbd2008-06-26 21:28:10 +0200315 isolate - enable device isolation (each device, as far
316 as possible, will get its own protection
Joerg Roedel3ce1f932008-11-17 15:09:20 +0100317 domain) [default]
Joerg Roedele5e1f602008-11-17 15:07:17 +0100318 share - put every device behind one IOMMU into the
319 same protection domain
FUJITA Tomonoriafa9fdc2008-09-20 01:23:30 +0900320 fullflush - enable flushing of IO/TLB entries when
321 they are unmapped. Otherwise they are
322 flushed before they will be reused, which
323 is a lot of faster
324
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325 amijoy.map= [HW,JOY] Amiga joystick support
326 Map of devices attached to JOY0DAT and JOY1DAT
327 Format: <a>,<b>
328 See also Documentation/kernel/input/joystick.txt
329
330 analog.map= [HW,JOY] Analog joystick and gamepad support
331 Specifies type or capabilities of an analog joystick
332 connected to one of 16 gameports
333 Format: <type1>,<type2>,..<type16>
334
Randy Dunlapa9913042005-10-23 12:57:11 -0700335 apc= [HW,SPARC]
336 Power management functions (SPARCstation-4/5 + deriv.)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 Format: noidle
338 Disable APC CPU standby support. SPARCstation-Fox does
339 not play well with APC CPU idle - disable it if you have
340 APC and your system crashes randomly.
341
Randy Dunlapca1eda22009-05-06 16:02:58 -0700342 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Randy Dunlapc8facbb2007-07-31 00:37:40 -0700343 Change the output verbosity whilst booting
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 Format: { quiet (default) | verbose | debug }
345 Change the amount of debugging information output
346 when initialising the APIC and IO-APIC components.
Randy Dunlapa9913042005-10-23 12:57:11 -0700347
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 apm= [APM] Advanced Power Management
Pavel Machek71f77052008-07-04 09:59:43 -0700349 See header of arch/x86/kernel/apm_32.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
352 Format: <io>,<irq>,<nodeID>
353
354 ataflop= [HW,M68k]
355
356 atarimouse= [HW,MOUSE] Atari Mouse
357
358 atascsi= [HW,SCSI] Atari SCSI
359
360 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
361 EzKey and similar keyboards
362
363 atkbd.reset= [HW] Reset keyboard during initialization
364
Randy Dunlapa9913042005-10-23 12:57:11 -0700365 atkbd.set= [HW] Select keyboard code set
366 Format: <int> (2 = AT (default), 3 = PS/2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367
368 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
369 keyboards
370
371 atkbd.softraw= [HW] Choose between synthetic and real raw mode
372 Format: <bool> (0 = real, 1 = synthetic (default))
Randy Dunlapa9913042005-10-23 12:57:11 -0700373
374 atkbd.softrepeat= [HW]
375 Use software keyboard repeat
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376
377 autotest [IA64]
378
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 baycom_epp= [HW,AX25]
380 Format: <io>,<mode>
Randy Dunlapa9913042005-10-23 12:57:11 -0700381
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
383 Format: <io>,<mode>
384 See header of drivers/net/hamradio/baycom_par.c.
385
Randy Dunlapa9913042005-10-23 12:57:11 -0700386 baycom_ser_fdx= [HW,AX25]
387 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 Format: <io>,<irq>,<mode>[,<baud>]
389 See header of drivers/net/hamradio/baycom_ser_fdx.c.
390
Randy Dunlapa9913042005-10-23 12:57:11 -0700391 baycom_ser_hdx= [HW,AX25]
392 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 Format: <io>,<irq>,<mode>
394 See header of drivers/net/hamradio/baycom_ser_hdx.c.
395
Randy Dunlapbfe8df32007-10-16 01:23:46 -0700396 boot_delay= Milliseconds to delay each printk during boot.
397 Values larger than 10 seconds (10000) are changed to
398 no delay (0).
399 Format: integer
400
Andreas Herrmann35fc9082008-08-20 14:08:58 -0700401 bootmem_debug [KNL] Enable bootmem allocator debug messages.
402
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
Randy Dunlapa9913042005-10-23 12:57:11 -0700404 bttv.radio= Most important insmod options are available as
405 kernel args too.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
407 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
408
409 BusLogic= [HW,SCSI]
410 See drivers/scsi/BusLogic.c, comment before function
411 BusLogic_ParseDriverOptions().
412
413 c101= [NET] Moxa C101 synchronous serial card
414
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700415 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 Sometimes CPU hardware bugs make them report the cache
417 size incorrectly. The kernel will attempt work arounds
418 to fix known problems, but for some CPUs it is not
419 possible to determine what the correct size should be.
420 This option provides an override for these situations.
421
James Morris20510f22007-10-16 23:31:32 -0700422 capability.disable=
423 [SECURITY] Disable capabilities. This would normally
424 be used only if an alternative security model is to be
425 configured. Potentially dangerous and should only be
426 used if you are entirely sure of the consequences.
427
Sebastian Ott14ff56b2008-01-26 14:10:37 +0100428 ccw_timeout_log [S390]
429 See Documentation/s390/CommonIO for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430
Paul Menage8bab8dd2008-04-04 14:29:57 -0700431 cgroup_disable= [KNL] Disable a particular controller
432 Format: {name of the controller(s) to disable}
433 {Currently supported controllers - "memory"}
434
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 checkreqprot [SELINUX] Set initial checkreqprot flag value.
436 Format: { "0" | "1" }
437 See security/selinux/Kconfig help text.
Randy Dunlapa9913042005-10-23 12:57:11 -0700438 0 -- check protection applied by kernel (includes
439 any implied execute protection).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 1 -- check protection requested by application.
441 Default value is set via a kernel config option.
Randy Dunlapa9913042005-10-23 12:57:11 -0700442 Value can be changed at runtime via
443 /selinux/checkreqprot.
444
Sebastian Ott661ca0d2008-01-26 14:10:36 +0100445 cio_ignore= [S390]
446 See Documentation/s390/CommonIO for details.
447
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700448 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
john stultz734efb42006-06-26 00:25:05 -0700449 [Deprecated]
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200450 Forces specified clocksource (if available) to be used
john stultz734efb42006-06-26 00:25:05 -0700451 when calculating gettimeofday(). If specified
Matt LaPlante3f6dee92006-10-03 22:45:33 +0200452 clocksource is not available, it defaults to PIT.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453 Format: { pit | tsc | cyclone | pmtmr }
454
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700455 clocksource= [GENERIC_TIME] Override the default clocksource
456 Format: <string>
457 Override the default clocksource and use the clocksource
458 with the name specified.
459 Some clocksource names to choose from, depending on
460 the platform:
461 [all] jiffies (this is the base, fallback clocksource)
462 [ACPI] acpi_pm
463 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
464 pxa_timer,timer3,32k_counter,timer0_1
465 [AVR32] avr32
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700466 [X86-32] pit,hpet,tsc,vmi-timer;
Randy Dunlap3d6ac982007-05-23 13:58:16 -0700467 scx200_hrt on Geode; cyclone on IBM x440
468 [MIPS] MIPS
469 [PARISC] cr16
470 [S390] tod
471 [SH] SuperH
472 [SPARC64] tick
473 [X86-64] hpet,tsc
474
Andi Kleenac72e782008-01-30 13:33:21 +0100475 clearcpuid=BITNUM [X86]
476 Disable CPUID feature X for the kernel. See
Randy Dunlap07983f02009-01-06 14:42:41 -0800477 arch/x86/include/asm/cpufeature.h for the valid bit
478 numbers. Note the Linux specific bits are not necessarily
Andi Kleenac72e782008-01-30 13:33:21 +0100479 stable over kernel options, but the vendor specific
480 ones should be.
481 Also note that user programs calling CPUID directly
482 or using the feature without checking anything
483 will still see it. This just prevents it from
484 being used by the kernel or shown in /proc/cpuinfo.
485 Also note the kernel might malfunction if you disable
486 some critical bits.
487
Robert Jennings14f966e2009-04-15 05:55:32 +0000488 cmo_free_hint= [PPC] Format: { yes | no }
489 Specify whether pages are marked as being inactive
490 when they are freed. This is used in CMO environments
491 to determine OS memory pressure for page stealing by
492 a hypervisor.
493 Default: yes
494
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530495 code_bytes [X86] How many bytes of object code to print
Arjan van de Vena25bd942008-01-30 13:33:08 +0100496 in an oops report.
Chuck Ebbert86c41832007-02-13 13:26:25 +0100497 Range: 0 - 8192
498 Default: 64
499
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 com20020= [HW,NET] ARCnet - COM20020 chipset
Randy Dunlapa9913042005-10-23 12:57:11 -0700501 Format:
502 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503
504 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
505 Format: <io>[,<irq>]
506
Randy Dunlapa9913042005-10-23 12:57:11 -0700507 com90xx= [HW,NET]
508 ARCnet - COM90xx chipset (memory-mapped buffers)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 Format: <io>[,<irq>[,<memstart>]]
510
511 condev= [HW,S390] console device
512 conmode=
Randy Dunlapa9913042005-10-23 12:57:11 -0700513
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514 console= [KNL] Output console device and options.
515
516 tty<n> Use the virtual console device <n>.
517
518 ttyS<n>[,options]
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800519 ttyUSB0[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520 Use the specified serial port. The options are of
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800521 the form "bbbbpnf", where "bbbb" is the baud rate,
522 "p" is parity ("n", "o", or "e"), "n" is number of
523 bits, and "f" is flow control ("r" for RTS or
524 omit it). Default is "9600n8".
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525
Randy Dunlapf1a1c2d2006-03-25 03:08:17 -0800526 See Documentation/serial-console.txt for more
527 information. See
528 Documentation/networking/netconsole.txt for an
529 alternative.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530
Yinghai Lu18a8bd92007-07-15 23:37:59 -0700531 uart[8250],io,<addr>[,options]
532 uart[8250],mmio,<addr>[,options]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 Start an early, polled-mode console on the 8250/16550
534 UART at the specified I/O port or MMIO address,
535 switching to the matching ttyS device later. The
536 options are the same as for ttyS, above.
537
Samuel Thibaultf7511d52008-04-30 00:54:51 -0700538 If the device connected to the port is not a TTY but a braille
539 device, prepend "brl," before the device type, for instance
540 console=brl,ttyS0
541 For now, only VisioBraille is supported.
542
Daniel Mackf324edc2009-06-16 15:33:52 -0700543 consoleblank= [KNL] The console blank (screen saver) timeout in
544 seconds. Defaults to 10*60 = 10mins. A value of 0
545 disables the blank timer.
546
Hidehiro Kawai4cb0e112009-01-06 14:42:47 -0800547 coredump_filter=
548 [KNL] Change the default value for
549 /proc/<pid>/coredump_filter.
550 See also Documentation/filesystems/proc.txt.
551
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Randy Dunlapa9913042005-10-23 12:57:11 -0700553 Format:
554 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555
Eric W. Biedermandc009d92005-06-25 14:57:52 -0700556 crashkernel=nn[KMG]@ss[KMG]
557 [KNL] Reserve a chunk of physical memory to
558 hold a kernel to switch to with kexec on panic.
559
Bernhard Wallefb391592007-10-18 23:41:02 -0700560 crashkernel=range1:size1[,range2:size2,...][@offset]
561 [KNL] Same as above, but depends on the memory
562 in the running system. The syntax of range is
563 start-[end] where start and end are both
564 a memory unit (amount[KMG]). See also
565 Documentation/kdump/kdump.txt for a example.
566
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567 cs89x0_dma= [HW,NET]
568 Format: <dma>
569
570 cs89x0_media= [HW,NET]
571 Format: { rj45 | aui | bnc }
Randy Dunlapa9913042005-10-23 12:57:11 -0700572
Randy Dunlapa9913042005-10-23 12:57:11 -0700573 dasd= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 See header of drivers/s390/block/dasd_devmap.c.
575
576 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
577 (one device per port)
578 Format: <port#>,<type>
579 See also Documentation/input/joystick-parport.txt
580
581 debug [KNL] Enable kernel debugging (events log level).
582
Ingo Molnarcae2ed92006-07-03 00:24:48 -0700583 debug_locks_verbose=
584 [KNL] verbose self-tests
585 Format=<0|1>
586 Print debugging info while doing the locking API
587 self-tests.
588 We default to 0 (no extra messages), setting it to
589 1 will print _a lot_ more information - normally
590 only useful to kernel developers.
591
Thomas Gleixner3ac7fe52008-04-30 00:55:01 -0700592 debug_objects [KNL] Enable object debugging
593
Kyle McMartin3e8ebb52009-03-01 20:41:41 -0500594 no_debug_objects
595 [KNL] Disable object debugging
596
Thomas Gleixnerd3af01f2008-07-15 15:04:56 +0200597 debugpat [X86] Enable PAT debugging
598
Robert P. J. Day2d27a962008-02-03 15:18:45 +0200599 decnet.addr= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 Format: <area>[,<node>]
601 See also Documentation/networking/decnet.txt.
602
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700603 default_hugepagesz=
604 [same as hugepagesz=] The size of the default
605 HugeTLB page size. This is the size represented by
606 the legacy /proc/ hugepages APIs, used for SHM, and
607 default size when mounting hugetlbfs filesystems.
608 Defaults to the default architecture's huge page size
609 if not specified.
Antonino A. Daplas55ff9782007-05-08 00:38:53 -0700610
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 dhash_entries= [KNL]
612 Set number of hash buckets for dentry cache.
Randy Dunlapa9913042005-10-23 12:57:11 -0700613
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614 digi= [HW,SERIAL]
615 IO parameters + enable/disable command.
616
617 digiepca= [HW,SERIAL]
618 See drivers/char/README.epca and
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000619 Documentation/serial/digiepca.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620
Yinghai Lu95ffa242008-04-29 03:52:33 -0700621 disable_mtrr_cleanup [X86]
Yinghai Lu95ffa242008-04-29 03:52:33 -0700622 The kernel tries to adjust MTRR layout from continuous
623 to discrete, to make X server driver able to add WB
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700624 entry later. This parameter disables that.
Yinghai Lu95ffa242008-04-29 03:52:33 -0700625
Yinghai Lu093af8d2008-01-30 13:33:32 +0100626 disable_mtrr_trim [X86, Intel and AMD only]
Jesse Barnes99fc8d42008-01-30 13:33:18 +0100627 By default the kernel will trim any uncacheable
628 memory out of your available memory pool based on
629 MTRR settings. This parameter disables that behavior,
630 possibly causing your machine to run very slowly.
631
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530632 disable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700633 Disable PIN 1 of APIC timer
634 Can be useful to work around chipset bugs.
635
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 dmasound= [HW,OSS] Sound subsystem buffers
637
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700638 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
639 this option disables the debugging code at boot.
640
641 dma_debug_entries=<number>
642 This option allows to tune the number of preallocated
643 entries for DMA-API debugging code. One entry is
644 required per DMA-API allocation. Use this if the
645 DMA-API debugging code disables itself because the
646 architectural default is too low.
647
Joerg Roedel1745de52009-05-22 21:49:51 +0200648 dma_debug_driver=<driver_name>
649 With this option the DMA-API debugging driver
650 filter feature can be enabled at boot time. Just
651 pass the driver to filter for as the parameter.
652 The filter can be disabled or changed to another
653 driver later using sysfs.
654
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655 dscc4.setup= [NET]
656
657 dtc3181e= [HW,SCSI]
658
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700659 dynamic_printk Enables pr_debug()/dev_dbg() calls if
660 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
661 These can also be switched on/off via
662 <debugfs>/dynamic_printk/modules
663
664 earlycon= [KNL] Output early console device and options.
665 uart[8250],io,<addr>[,options]
666 uart[8250],mmio,<addr>[,options]
667 Start an early, polled-mode console on the 8250/16550
668 UART at the specified I/O port or MMIO address.
669 The options are the same as for ttyS, above.
670
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530671 earlyprintk= [X86,SH,BLACKFIN]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672 earlyprintk=vga
673 earlyprintk=serial[,ttySn[,baudrate]]
Yinghai Lu5c059172008-07-24 17:29:40 -0700674 earlyprintk=dbgp
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675
Randy Dunlapa9913042005-10-23 12:57:11 -0700676 Append ",keep" to not disable it when the real console
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 takes over.
678
Yinghai Lu5c059172008-07-24 17:29:40 -0700679 Only vga or serial or usb debug port at a time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680
681 Currently only ttyS0 and ttyS1 are supported.
682
683 Interaction with the standard serial driver is not
684 very good.
685
686 The VGA output is eventually overwritten by the real
687 console.
688
689 eata= [HW,SCSI]
690
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691 edd= [EDD]
Tim Gardner8c4dd602008-04-29 01:02:45 -0700692 Format: {"off" | "on" | "skip[mbr]"}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 eisa_irq_edge= [PARISC,HW]
695 See header of drivers/parisc/eisa.c.
696
Alan Coxcd4f0ef2007-07-31 00:37:59 -0700697 elanfreq= [X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 See comment before function elanfreq_setup() in
Pavel Machek71f77052008-07-04 09:59:43 -0700699 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700
701 elevator= [IOSCHED]
Randy Dunlap16ab3ad2006-01-14 13:21:20 -0800702 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
Randy Dunlapa9913042005-10-23 12:57:11 -0700703 See Documentation/block/as-iosched.txt and
704 Documentation/block/deadline-iosched.txt for details.
705
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +0530706 elfcorehdr= [IA64,PPC,SH,X86]
Randy Dunlapa9913042005-10-23 12:57:11 -0700707 Specifies physical address of start of kernel core
Vivek Goyalaac04b32006-01-09 20:51:47 -0800708 image elf header. Generally kexec loader will
709 pass this option to capture kernel.
710 See Documentation/kdump/kdump.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700712 enable_mtrr_cleanup [X86]
713 The kernel tries to adjust MTRR layout from continuous
714 to discrete, to make X server driver able to add WB
715 entry later. This parameter enables that.
716
Randy Dunlapca1eda22009-05-06 16:02:58 -0700717 enable_timer_pin_1 [X86]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700718 Enable PIN 1 of APIC timer
719 Can be useful to work around chipset bugs
720 (in particular on some ATI chipsets).
721 The kernel tries to set a reasonable default.
722
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 enforcing [SELINUX] Set initial enforcing status.
724 Format: {"0" | "1"}
725 See security/selinux/Kconfig help text.
726 0 -- permissive (log only, no denials).
727 1 -- enforcing (deny and log).
728 Default value is 0.
729 Value can be changed at runtime via /selinux/enforce.
730
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731 ether= [HW,NET] Ethernet cards parameters
732 This option is obsoleted by the "netdev=" option, which
733 has equivalent usage. See its documentation for details.
734
735 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
736 Format: <io>[,<irq>]
737
Akinobu Mitade1ba092006-12-08 02:39:42 -0800738 failslab=
739 fail_page_alloc=
740 fail_make_request=[KNL]
741 General fault injection mechanism.
742 Format: <interval>,<probability>,<space>,<times>
743 See also /Documentation/fault-injection/.
744
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 fd_mcs= [HW,SCSI]
746 See header of drivers/scsi/fd_mcs.c.
747
748 fdomain= [HW,SCSI]
749 See header of drivers/scsi/fdomain.c.
750
751 floppy= [HW]
Randy Dunlap31c00fc2008-11-13 21:33:24 +0000752 See Documentation/blockdev/floppy.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753
Alex Chiangf13ae302008-05-08 14:03:23 -0600754 force_pal_cache_flush
755 [IA-64] Avoid check_sal_cache_flush which may hang on
756 buggy SAL_CACHE_FLUSH implementations. Using this
757 parameter will force ia64_sal_cache_flush to call
758 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
759
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100760 ftrace=[tracer]
Steven Rostedt2af15d62009-05-28 13:37:24 -0400761 [FTRACE] will set and start the specified tracer
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100762 as early as possible in order to facilitate early
763 boot debugging.
764
765 ftrace_dump_on_oops
Steven Rostedt2af15d62009-05-28 13:37:24 -0400766 [FTRACE] will dump the trace buffers on oops.
767
768 ftrace_filter=[function-list]
769 [FTRACE] Limit the functions traced by the function
770 tracer at boot up. function-list is a comma separated
771 list of functions. This list can be changed at run
772 time by the set_ftrace_filter file in the debugfs
773 tracing directory.
774
775 ftrace_notrace=[function-list]
776 [FTRACE] Do not trace the functions specified in
777 function-list. This list can be changed at run time
778 by the set_ftrace_notrace file in the debugfs
779 tracing directory.
Peter Zijlstrad9e54072008-11-01 19:57:37 +0100780
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 gamecon.map[2|3]=
782 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
783 support via parallel port (up to 5 devices per port)
784 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
785 See also Documentation/input/joystick-parport.txt
786
787 gamma= [HW,DRM]
788
Yinghai Luaaf23042008-01-30 13:33:09 +0100789 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
790 Format: off | on
791 default: on
792
Peter Oberparleiter2521f2c2009-06-17 16:28:08 -0700793 gcov_persist= [GCOV] When non-zero (default), profiling data for
794 kernel modules is saved and remains accessible via
795 debugfs, even when the module is unloaded/reloaded.
796 When zero, profiling data is discarded and associated
797 debugfs files are removed at module unload time.
798
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 gdth= [HW,SCSI]
800 See header of drivers/scsi/gdth.c.
801
802 gpt [EFI] Forces disk with valid GPT signature but
803 invalid Protective MBR to be treated as GPT.
804
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805 gvp11= [HW,SCSI]
806
807 hashdist= [KNL,NUMA] Large hashes allocated during boot
808 are distributed across NUMA nodes. Defaults on
Hugh Dickins429aa0f2009-05-06 16:02:51 -0700809 for 64bit NUMA, off otherwise.
Randy Dunlapa9913042005-10-23 12:57:11 -0700810 Format: 0 | 1 (for off | on)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700811
812 hcl= [IA-64] SGI's Hardware Graph compatibility layer
813
814 hd= [EIDE] (E)IDE hard drive subsystem geometry
815 Format: <cyl>,<head>,<sect>
816
Linus Torvalds1da177e2005-04-16 15:20:36 -0700817 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
818 size of <nn>. This works even on boxes that have no
819 highmem otherwise. This also works to reduce highmem
820 size on bigger boxes.
821
Thomas Gleixner54cdfdb2007-02-16 01:28:11 -0800822 highres= [KNL] Enable/disable high resolution timer mode.
823 Valid parameters: "on", "off"
824 Default: "on"
825
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 hisax= [HW,ISDN]
827 See Documentation/isdn/README.HiSax.
828
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700829 hlt [BUGS=ARM,SH]
830
831 hpet= [X86-32,HPET] option to control HPET usage
832 Format: { enable (default) | disable | force |
833 verbose }
834 disable: disable HPET and use PIT instead
835 force: allow force enabled of undocumented chips (ICH4,
836 VIA, nVidia)
837 verbose: show contents of HPET registers during setup
838
Andi Kleenb4718e62008-07-23 21:27:51 -0700839 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
840 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
Jon Tollefson0d9ea752008-07-23 21:27:56 -0700841 On x86-64 and powerpc, this option can be specified
842 multiple times interleaved with hugepages= to reserve
843 huge pages of different sizes. Valid pages sizes on
844 x86-64 are 2M (when the CPU supports "pse") and 1G
845 (when the CPU supports the "pdpe1gb" cpuinfo flag)
Andi Kleenb4718e62008-07-23 21:27:51 -0700846 Note that 1GB pages can only be allocated at boot time
847 using hugepages= and not freed afterwards.
Paul Mundt6902aa82008-09-21 17:14:42 +0900848
Hendrik Brueckner555d61d2009-01-09 12:15:02 +0100849 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
850 terminal devices. Valid values: 0..8
Hendrik Brueckner431429f2009-03-26 15:23:55 +0100851 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
852 If specified, z/VM IUCV HVC accepts connections
853 from listed z/VM user IDs only.
Hendrik Bruecknercef71252008-12-25 13:39:55 +0100854
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700855 i2c_bus= [HW] Override the default board specific I2C bus speed
Jarkko Nikula79547632009-03-23 18:07:48 -0700856 or register an additional I2C bus that is not
857 registered from board initialization code.
Jarkko Nikula3a853fb2009-03-23 18:07:47 -0700858 Format:
859 <bus_id>,<clkrate>
860
Jiri Kosina36d95732008-10-06 02:51:09 -0400861 i8042.debug [HW] Toggle i8042 debug mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 i8042.direct [HW] Put keyboard port into non-translated mode
Matt LaPlante84eb8d02006-10-03 22:53:09 +0200863 i8042.dumbkbd [HW] Pretend that controller can only read data from
864 keyboard and cannot control its state
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865 (Don't attempt to blink the leds)
866 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
Dmitry Torokhov945ef0d2005-09-04 01:42:00 -0500867 i8042.nokbd [HW] Don't check/create keyboard port
Jiri Kosina75d08c72008-03-13 16:13:59 -0400868 i8042.noloop [HW] Disable the AUX Loopback command while probing
869 for the AUX port
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870 i8042.nomux [HW] Don't check presence of an active multiplexing
871 controller
872 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
873 controllers
874 i8042.panicblink=
875 [HW] Frequency with which keyboard LEDs should blink
876 when kernel panics (default is 0.5 sec)
877 i8042.reset [HW] Reset the controller during init and cleanup
878 i8042.unlock [HW] Unlock (ignore) the keylock
879
880 i810= [HW,DRM]
881
Dmitry Torokhove70c9d52005-06-25 14:54:25 -0700882 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
883 indicates that the driver is running on unsupported
884 hardware.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
886 does not match list of supported models.
887 i8k.power_status
888 [HW] Report power status in /proc/i8k
889 (disabled by default)
890 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
891 capability is set.
892
893 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
894 See Documentation/mca.txt.
895
896 icn= [HW,ISDN]
897 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
898
David Fries0af80c02009-02-25 20:28:21 +0100899 ide-core.nodma= [HW] (E)IDE subsystem
900 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
Bartlomiej Zolnierkiewicz075affc2009-06-07 13:52:52 +0200901 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
902 .cdrom .chs .ignore_cable are additional options
Randy Dunlap1c10e932008-03-07 21:53:50 +0100903 See Documentation/ide/ide.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700905 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
906 Claim all unknown PCI IDE storage controllers.
907
Andi Kleenf039b752007-05-02 19:27:12 +0200908 idle= [X86]
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800909 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
910 Poll forces a polling idle loop that can slightly
911 improve the performance of waking up a idle CPU, but
912 will use a lot of power and make the system run hot.
913 Not recommended.
914 idle=mwait: On systems which support MONITOR/MWAIT but
915 the kernel chose to not use it because it doesn't save
916 as much power as a normal idle loop, use the
917 MONITOR/MWAIT idle loop anyways. Performance should be
918 the same as idle=poll.
919 idle=halt: Halt is forced to be used for CPU idle.
Zhao Yakuic1e3b372008-06-24 17:58:53 +0800920 In such case C2/C3 won't be used again.
Randy Dunlapada9cfd2008-12-19 10:57:32 -0800921 idle=nomwait: Disable mwait for CPU C-states
Randy Dunlapa9913042005-10-23 12:57:11 -0700922
Ingo Molnar792908222006-12-06 20:40:51 -0800923 ignore_loglevel [KNL]
924 Ignore loglevel setting - this will print /all/
925 kernel messages to the console. Useful for debugging.
926
Linus Torvalds1da177e2005-04-16 15:20:36 -0700927 ihash_entries= [KNL]
928 Set number of hash buckets for inode cache.
929
Mimi Zohar3323eec2009-02-04 09:06:58 -0500930 ima_audit= [IMA]
931 Format: { "0" | "1" }
932 0 -- integrity auditing messages. (Default)
933 1 -- enable informational integrity auditing messages.
934
935 ima_hash= [IMA]
936 Formt: { "sha1" | "md5" }
937 default: "sha1"
938
Eric Paris5789ba32009-05-21 15:47:06 -0400939 ima_tcb [IMA]
940 Load a policy which meets the needs of the Trusted
941 Computing Base. This means IMA will measure all
942 programs exec'd, files mmap'd for exec, and all files
943 opened for read by uid=0.
944
Linus Torvalds1da177e2005-04-16 15:20:36 -0700945 in2000= [HW,SCSI]
946 See header of drivers/scsi/in2000.c.
947
948 init= [KNL]
949 Format: <full_path>
950 Run specified binary instead of /sbin/init as init
951 process.
952
953 initcall_debug [KNL] Trace initcalls as they are executed. Useful
954 for working out where the kernel is dying during
955 startup.
956
957 initrd= [BOOT] Specify the location of the initial ramdisk
958
959 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
960 Format: <irq>
961
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700962 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
Kyle McMartin0cd5c3c2009-02-04 14:29:19 -0800963 on
964 Enable intel iommu driver.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700965 off
966 Disable intel iommu driver.
967 igfx_off [Default Off]
968 By default, gfx is mapped as normal device. If a gfx
969 device has a dedicated DMAR unit, the DMAR unit is
970 bypassed by not enabling DMAR with this option. In
971 this case, gfx device will use physical address for
972 DMA.
Keshavamurthy, Anil S7d3b03c2007-10-21 16:41:53 -0700973 forcedac [x86_64]
974 With this option iommu will not optimize to look
975 for io virtual address below 32 bit forcing dual
976 address cycle on pci bus for cards supporting greater
977 than 32 bit addressing. The default is to look
978 for translation below 32 bit and if not available
979 then look in the higher range.
mark gross5e0d2a62008-03-04 15:22:08 -0800980 strict [Default Off]
981 With this option on every unmap_single operation will
982 result in a hardware IOTLB flush operation as opposed
983 to batching them for performance.
Keshavamurthy, Anil Sba395922007-10-21 16:41:49 -0700984
Randy Dunlap0cb55ad2009-04-05 15:55:22 -0700985 inttest= [IA64]
986
987 iomem= Disable strict checking of access to MMIO memory
988 strict regions from userspace.
989 relaxed
990
991 iommu= [x86]
992 off
993 force
994 noforce
995 biomerge
996 panic
997 nopanic
998 merge
999 nomerge
1000 forcesac
1001 soft
Fenghua Yu4ed0d3e2009-04-24 17:30:20 -07001002 pt [x86, IA64]
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001003
1004 io7= [HW] IO7 for Marvel based alpha systems
1005 See comment before marvel_specify_io7 in
1006 arch/alpha/kernel/core_marvel.c.
1007
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301008 io_delay= [X86] I/O delay method
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001009 0x80
1010 Standard port 0x80 based delay
1011 0xed
1012 Alternate port 0xed based delay (needed on some systems)
Rene Hermanb02aae92008-01-30 13:30:05 +01001013 udelay
Ingo Molnar6e7c4022008-01-30 13:30:05 +01001014 Simple two microseconds delay
1015 none
1016 No delay
Rene Hermanb02aae92008-01-30 13:30:05 +01001017
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 ip= [IP_PNP]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001019 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020
1021 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001022 See comment before ip2_setup() in
1023 drivers/char/ip2/ip2base.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024
1025 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1026 See header of drivers/scsi/ips.c.
1027
Alan Cox200803d2005-06-28 20:45:18 -07001028 irqfixup [HW]
1029 When an interrupt is not handled search all handlers
1030 for it. Intended to get systems with badly broken
1031 firmware running.
1032
1033 irqpoll [HW]
1034 When an interrupt is not handled search all handlers
1035 for it. Also check all handlers each timer
1036 interrupt. Intended to get systems with badly broken
1037 firmware running.
1038
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039 isapnp= [ISAPNP]
Randy Dunlapa9913042005-10-23 12:57:11 -07001040 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041
1042 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Derek Fults22f2e282006-12-06 20:37:11 -08001043 Format:
1044 <cpu number>,...,<cpu number>
1045 or
Li Zefanb225d442008-11-06 12:53:39 -08001046 <cpu number>-<cpu number>
1047 (must be a positive range in ascending order)
Derek Fults22f2e282006-12-06 20:37:11 -08001048 or a mixture
1049 <cpu number>,...,<cpu number>-<cpu number>
Li Zefanb225d442008-11-06 12:53:39 -08001050
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051 This option can be used to specify one or more CPUs
1052 to isolate from the general SMP balancing and scheduling
Li Zefanb225d442008-11-06 12:53:39 -08001053 algorithms. You can move a process onto or off an
1054 "isolated" CPU via the CPU affinity syscalls or cpuset.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055 <cpu number> begins at 0 and the maximum value is
1056 "number of CPUs in system - 1".
1057
1058 This option is the preferred way to isolate CPUs. The
Randy Dunlapa9913042005-10-23 12:57:11 -07001059 alternative -- manually setting the CPU mask of all
1060 tasks in the system -- can cause problems and
1061 suboptimal load balancer performance.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062
Randy Dunlapa9913042005-10-23 12:57:11 -07001063 iucv= [HW,NET]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064
1065 js= [HW,JOY] Analog joystick
1066 See Documentation/input/joystick.txt.
1067
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001068 keepinitrd [HW,ARM]
1069
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301070 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Mel Gormaned7ed362007-07-17 04:03:14 -07001071 specifies the amount of memory usable by the kernel
1072 for non-movable allocations. The requested amount is
1073 spread evenly throughout all nodes in the system. The
1074 remaining memory in each node is used for Movable
1075 pages. In the event, a node is too small to have both
1076 kernelcore and Movable pages, kernelcore pages will
1077 take priority and other nodes will have a larger number
1078 of kernelcore pages. The Movable zone is used for the
1079 allocation of pages that may be reclaimed or moved
1080 by the page migration subsystem. This means that
1081 HugeTLB pages may not be allocated from this zone.
1082 Note that allocations like PTEs-from-HighMem still
1083 use the HighMem zone if it exists, and the Normal
1084 zone if it does not.
1085
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001086 kgdboc= [HW] kgdb over consoles.
1087 Requires a tty driver that supports console polling.
Matt LaPlante19f59462009-04-27 15:06:31 +02001088 (only serial supported for now)
Jason Wessel6cdf6e02008-04-17 20:05:38 +02001089 Format: <serial_device>[,baud]
1090
Florian Fainelli9bed90c62008-08-23 18:54:37 +02001091 kmac= [MIPS] korina ethernet MAC address.
1092 Configure the RouterBoard 532 series on-chip
1093 Ethernet adapter MAC address.
1094
Catalin Marinas04f70332009-06-11 13:22:39 +01001095 kmemleak= [KNL] Boot-time kmemleak enable/disable
1096 Valid arguments: on, off
1097 Default: on
1098
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301099 kstack=N [X86] Print N words from the kernel stack
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001100 in oops dumps.
1101
Andre Przywarafef07aa2009-07-10 14:20:35 +02001102 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1103 Default is 0 (don't ignore, but inject #GP)
1104
1105 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1106 Default is 1 (enabled)
1107
1108 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1109 Default is 0 (off)
1110
1111 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1112 for all guests.
1113 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1114
1115 kvm-intel.bypass_guest_pf=
1116 [KVM,Intel] Disables bypassing of guest page faults
1117 on Intel chips. Default is 1 (enabled)
1118
1119 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1120 (virtualized MMU) support on capable Intel chips.
1121 Default is 1 (enabled)
1122
1123 kvm-intel.emulate_invalid_guest_state=
1124 [KVM,Intel] Enable emulation of invalid guest states
1125 Default is 0 (disabled)
1126
1127 kvm-intel.flexpriority=
1128 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1129 Default is 1 (enabled)
1130
1131 kvm-intel.unrestricted_guest=
1132 [KVM,Intel] Disable unrestricted guest feature
1133 (virtualized real and unpaged mode) on capable
1134 Intel chips. Default is 1 (enabled)
1135
1136 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1137 feature (tagged TLBs) on capable Intel chips.
1138 Default is 1 (enabled)
1139
Linus Torvalds1da177e2005-04-16 15:20:36 -07001140 l2cr= [PPC]
1141
Robert Brosea78bfbf2008-03-29 07:20:23 +11001142 l3cr= [PPC]
1143
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001144 lapic [X86-32,APIC] Enable the local APIC even if BIOS
Randy Dunlapa9913042005-10-23 12:57:11 -07001145 disabled it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001146
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301147 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
Randy Dunlapada9cfd2008-12-19 10:57:32 -08001148 in C2 power state.
Thomas Gleixnere585bef2007-03-23 16:08:01 +01001149
FD Camifcb71f62008-01-06 19:08:56 +01001150 libata.dma= [LIBATA] DMA control
1151 libata.dma=0 Disable all PATA and SATA DMA
1152 libata.dma=1 PATA and SATA Disk DMA only
1153 libata.dma=2 ATAPI (CDROM) DMA only
1154 libata.dma=4 Compact Flash DMA only
1155 Combinations also work, so libata.dma=3 enables DMA
1156 for disks and CDROMs, but not CFs.
Michael Prokop20308872009-08-06 00:14:10 +02001157
1158 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1159 libata.ignore_hpa=0 keep BIOS limits (default)
1160 libata.ignore_hpa=1 ignore limits, using full disk
FD Camifcb71f62008-01-06 19:08:56 +01001161
Dave Jones78e70c22007-09-27 11:50:13 -04001162 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1163 when set.
1164 Format: <int>
1165
Tejun Heo33267322008-02-13 09:15:09 +09001166 libata.force= [LIBATA] Force configurations. The format is comma
1167 separated list of "[ID:]VAL" where ID is
1168 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1169 matching port, link or device. Basically, it matches
1170 the ATA ID string printed on console by libata. If
1171 the whole ID part is omitted, the last PORT and DEVICE
1172 values are used. If ID hasn't been specified yet, the
1173 configuration applies to all ports, links and devices.
1174
1175 If only DEVICE is omitted, the parameter applies to
1176 the port and all links and devices behind it. DEVICE
1177 number of 0 either selects the first device or the
1178 first fan-out link behind PMP device. It does not
1179 select the host link. DEVICE number of 15 selects the
1180 host link and device attached to it.
1181
1182 The VAL specifies the configuration to force. As long
1183 as there's no ambiguity shortcut notation is allowed.
1184 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1185 The following configurations can be forced.
1186
1187 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1188 Any ID with matching PORT is used.
1189
1190 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1191
1192 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1193 udma[/][16,25,33,44,66,100,133] notation is also
1194 allowed.
1195
1196 * [no]ncq: Turn on or off NCQ.
1197
Tejun Heo05944bd2008-08-13 20:19:09 +09001198 * nohrst, nosrst, norst: suppress hard, soft
1199 and both resets.
1200
Tejun Heo33267322008-02-13 09:15:09 +09001201 If there are multiple matching configurations changing
1202 the same attribute, the last one is used.
1203
Randy Dunlap7c4be252009-01-06 14:42:44 -08001204 lmb=debug [KNL] Enable lmb debug messages.
1205
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206 load_ramdisk= [RAM] List of ramdisks to load from floppy
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001207 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001208
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001209 lockd.nlm_grace_period=P [NFS] Assign grace period.
1210 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211
Randy Dunlapa6b25b62006-01-14 13:21:19 -08001212 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1213 Format: <integer>
1214
1215 lockd.nlm_timeout=T [NFS] Assign timeout value.
1216 Format: <integer>
1217
1218 lockd.nlm_udpport=M [NFS] Assign UDP port.
1219 Format: <integer>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220
1221 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1222 Format: <irq>
1223
1224 loglevel= All Kernel Messages with a loglevel smaller than the
1225 console loglevel will be printed to the console. It can
1226 also be changed with klogd or other programs. The
1227 loglevels are defined as follows:
1228
1229 0 (KERN_EMERG) system is unusable
1230 1 (KERN_ALERT) action must be taken immediately
1231 2 (KERN_CRIT) critical conditions
1232 3 (KERN_ERR) error conditions
1233 4 (KERN_WARNING) warning conditions
1234 5 (KERN_NOTICE) normal but significant condition
1235 6 (KERN_INFO) informational
1236 7 (KERN_DEBUG) debug-level messages
1237
1238 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
Randy Dunlapa9913042005-10-23 12:57:11 -07001239 Format: { n | nk | nM }
1240 n must be a power of two. The default size
1241 is set in the kernel config file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242
Randy Dunlapaccaa242007-10-16 01:29:37 -07001243 logo.nologo [FB] Disables display of the built-in Linux logo.
1244 This may be used to provide more screen space for
1245 kernel log messages and is useful when debugging
1246 kernel boot problems.
1247
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248 lp=0 [LP] Specify parallel ports to use, e.g,
1249 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1250 lp=reset first parallel port). 'lp=0' disables the
1251 lp=auto printer driver. 'lp=reset' (which can be
1252 specified in addition to the ports) causes
1253 attached printers to be reset. Using
1254 lp=port1,port2,... specifies the parallel ports
1255 to associate lp devices with, starting with
1256 lp0. A port specification may be 'none' to skip
1257 that lp device, or a parport name such as
1258 'parport0'. Specifying 'lp=auto' instead of a
1259 port specification list means that device IDs
1260 from each port should be examined, to see if
1261 an IEEE 1284-compliant printer is attached; if
1262 so, the driver will manage that printer.
1263 See also header of drivers/char/lp.c.
1264
1265 lpj=n [KNL]
1266 Sets loops_per_jiffy to given constant, thus avoiding
1267 time-consuming boot-time autodetection (up to 250 ms per
1268 CPU). 0 enables autodetection (default). To determine
1269 the correct value for your kernel, boot with normal
1270 autodetection and see what value is printed. Note that
1271 on SMP systems the preset will be applied to all CPUs,
1272 which is likely to cause problems if your CPUs need
1273 significantly divergent settings. An incorrect value
1274 will cause delays in the kernel to be wrong, leading to
1275 unpredictable I/O errors and other breakage. Although
1276 unlikely, in the extreme case this might damage your
1277 hardware.
1278
1279 ltpc= [NET]
1280 Format: <io>,<irq>,<dma>
1281
Randy Dunlapa9913042005-10-23 12:57:11 -07001282 mac5380= [HW,SCSI] Format:
1283 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284
Randy Dunlapa9913042005-10-23 12:57:11 -07001285 machvec= [IA64] Force the use of a particular machine-vector
1286 (machvec) in a generic kernel.
1287 Example: machvec=hpzx1_swiotlb
Linus Torvalds1da177e2005-04-16 15:20:36 -07001288
Wu Zhangjin3209e702009-07-02 23:27:12 +08001289 machtype= [Loongson] Share the same kernel image file between different
1290 yeeloong laptop.
1291 Example: machtype=lemote-yeeloong-2f-7inch
1292
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001293 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1294 than or equal to this physical address is ignored.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295
1296 maxcpus= [SMP] Maximum number of processors that an SMP kernel
Len Brown61ec7562007-08-16 03:34:22 -04001297 should make use of. maxcpus=n : n >= 0 limits the
1298 kernel to using 'n' processors. n=0 is a special case,
1299 it is equivalent to "nosmp", which also disables
1300 the IO APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001302 max_loop= [LOOP] Maximum number of loopback devices that can
1303 be mounted
1304 Format: <1-256>
Bob Picco2b2c3752005-06-29 18:00:00 -07001305
Randy Dunlapa9913042005-10-23 12:57:11 -07001306 max_luns= [SCSI] Maximum number of LUNs to probe.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 Should be between 1 and 2^32-1.
1308
1309 max_report_luns=
Randy Dunlapa9913042005-10-23 12:57:11 -07001310 [SCSI] Maximum number of LUNs received.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311 Should be between 1 and 16384.
1312
Linus Torvalds1da177e2005-04-16 15:20:36 -07001313 mcatest= [IA-64]
1314
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001315 mce [X86-32] Machine Check Exception
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316
Uwe Hermann71cced62008-10-20 09:32:21 -07001317 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
Andi Kleen909dd322007-10-17 18:04:38 +02001318
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319 md= [HW] RAID subsystems devices and level
1320 See Documentation/md.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07001321
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322 mdacon= [MDA]
1323 Format: <first>,<last>
1324 Specifies range of consoles to be captured by the MDA.
Randy Dunlapa9913042005-10-23 12:57:11 -07001325
Linus Torvalds1da177e2005-04-16 15:20:36 -07001326 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1327 Amount of memory to be used when the kernel is not able
1328 to see the whole system memory or for test.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001329 [X86-32] Use together with memmap= to avoid physical
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330 address space collisions. Without memmap= PCI devices
1331 could be placed at addresses belonging to unused RAM.
1332
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001333 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334 memory.
1335
Paul Mundt6902aa82008-09-21 17:14:42 +09001336 memchunk=nn[KMG]
1337 [KNL,SH] Allow user to override the default size for
1338 per-device physically contiguous DMA buffers.
1339
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301340 memmap=exactmap [KNL,X86] Enable setting of an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341 E820 memory map, as specified by the user.
1342 Such memmap=exactmap lines can be constructed based on
1343 BIOS output or other requirements. See the memmap=nn@ss
1344 option description.
1345
1346 memmap=nn[KMG]@ss[KMG]
1347 [KNL] Force usage of a specific region of memory
1348 Region of memory to be used, from ss to ss+nn.
1349
1350 memmap=nn[KMG]#ss[KMG]
1351 [KNL,ACPI] Mark specific memory as ACPI data.
1352 Region of memory to be used, from ss to ss+nn.
1353
1354 memmap=nn[KMG]$ss[KMG]
1355 [KNL,ACPI] Mark specific memory as reserved.
1356 Region of memory to be used, from ss to ss+nn.
Pavel Machek13128482008-03-24 12:29:43 -07001357 Example: Exclude memory from 0x18690000-0x1869ffff
1358 memmap=64K$0x18690000
1359 or
1360 memmap=0x10000$0x18690000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361
Jeremy Fitzhardinge9f077872008-09-07 01:51:34 -07001362 memory_corruption_check=0/1 [X86]
1363 Some BIOSes seem to corrupt the first 64k of
1364 memory when doing things like suspend/resume.
1365 Setting this option will scan the memory
1366 looking for corruption. Enabling this will
1367 both detect corruption and prevent the kernel
1368 from using the memory being corrupted.
1369 However, its intended as a diagnostic tool; if
1370 repeatable BIOS-originated corruption always
1371 affects the same memory, you can use memmap=
1372 to prevent the kernel from using that memory.
1373
1374 memory_corruption_check_size=size [X86]
1375 By default it checks for corruption in the low
1376 64k, making this memory unavailable for normal
1377 use. Use this parameter to scan for
1378 corruption in more or less memory.
1379
1380 memory_corruption_check_period=seconds [X86]
1381 By default it checks for corruption every 60
1382 seconds. Use this parameter to check at some
1383 other rate. 0 disables periodic checking.
1384
Yinghai Lucaadbdc2008-07-15 00:03:44 -07001385 memtest= [KNL,X86] Enable memtest
Yinghai Luc64df702008-03-21 18:56:19 -07001386 Format: <integer>
Yinghai Luc64df702008-03-21 18:56:19 -07001387 default : 0 <disable>
Andreas Herrmann9e5f6cf2009-02-25 11:30:45 +01001388 Specifies the number of memtest passes to be
1389 performed. Each pass selects another test
1390 pattern from a given set of patterns. Memtest
1391 fills the memory with this pattern, validates
1392 memory contents and reserves bad memory
1393 regions that are detected.
Yinghai Luc64df702008-03-21 18:56:19 -07001394
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395 meye.*= [HW] Set MotionEye Camera parameters
1396 See Documentation/video4linux/meye.txt.
1397
Andres Salomon8f368812007-10-12 23:04:06 +02001398 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1399 Multi-Function General Purpose Timers on AMD Geode
1400 platforms.
1401
Willy Tarreaue6c4dc62008-01-30 13:33:33 +01001402 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1403 the BIOS has incorrectly applied a workaround. TinyBIOS
1404 version 0.98 is known to be affected, 0.99 fixes the
1405 problem by letting the user disable the workaround.
1406
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407 mga= [HW,DRM]
1408
Randy Dunlap1c207f92008-11-19 15:36:16 -08001409 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1410 physical address is ignored.
1411
Michel Pollet39f45d72009-05-20 11:10:31 +01001412 mini2440= [ARM,HW,KNL]
1413 Format:[0..2][b][c][t]
1414 Default: "0tb"
1415 MINI2440 configuration specification:
1416 0 - The attached screen is the 3.5" TFT
1417 1 - The attached screen is the 7" TFT
1418 2 - The VGA Shield is attached (1024x768)
1419 Leaving out the screen size parameter will not load
1420 the TFT driver, and the framebuffer will be left
1421 unconfigured.
1422 b - Enable backlight. The TFT backlight pin will be
1423 linked to the kernel VESA blanking code and a GPIO
1424 LED. This parameter is not necessary when using the
1425 VGA shield.
1426 c - Enable the s3c camera interface.
1427 t - Reserved for enabling touchscreen support. The
1428 touchscreen support is not enabled in the mainstream
1429 kernel as of 2.6.30, a preliminary port can be found
1430 in the "bleeding edge" mini2440 support kernel at
1431 http://repo.or.cz/w/linux-2.6/mini2440.git
1432
Mel Gorman6b74ab92008-07-23 21:26:49 -07001433 mminit_loglevel=
1434 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1435 parameter allows control of the logging verbosity for
1436 the additional memory initialisation checks. A value
1437 of 0 disables mminit logging and a level of 4 will
1438 log everything. Information is printed at KERN_DEBUG
1439 so loglevel=8 may also need to be specified.
1440
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441 mousedev.tap_time=
1442 [MOUSE] Maximum time between finger touching and
1443 leaving touchpad surface for touch to be considered
1444 a tap and be reported as a left button click (for
1445 touchpads working in absolute mode only).
1446 Format: <msecs>
1447 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1448 reporting absolute coordinates, such as tablets
1449 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1450 reporting absolute coordinates, such as tablets
1451
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301452 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001453 is similar to kernelcore except it specifies the
1454 amount of memory used for migratable allocations.
1455 If both kernelcore and movablecore is specified,
1456 then kernelcore will be at *least* the specified
1457 value but may be more. If movablecore on its own
1458 is specified, the administrator must be careful
1459 that the amount of memory usable for all allocations
1460 is not too small.
1461
Linus Torvalds1da177e2005-04-16 15:20:36 -07001462 mpu401= [HW,OSS]
1463 Format: <io>,<irq>
1464
1465 MTD_Partition= [MTD]
1466 Format: <name>,<region-number>,<size>,<offset>
1467
Randy Dunlapa9913042005-10-23 12:57:11 -07001468 MTD_Region= [MTD] Format:
1469 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470
1471 mtdparts= [MTD]
Randy Dunlapc8facbb2007-07-31 00:37:40 -07001472 See drivers/mtd/cmdlinepart.c.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473
Rohit Hagargundgi5988af22009-05-12 13:46:57 -07001474 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1475
1476 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1477
1478 boundary - index of last SLC block on Flex-OneNAND.
1479 The remaining blocks are configured as MLC blocks.
1480 lock - Configure if Flex-OneNAND boundary should be locked.
1481 Once locked, the boundary cannot be changed.
1482 1 indicates lock status, 0 indicates unlock status.
1483
Ben Dooks9db829f2008-07-03 11:24:29 +01001484 mtdset= [ARM]
1485 ARM/S3C2412 JIVE boot control
1486
1487 See arch/arm/mach-s3c2412/mach-jive.c
1488
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489 mtouchusb.raw_coordinates=
Randy Dunlapa9913042005-10-23 12:57:11 -07001490 [HW] Make the MicroTouch USB driver use raw coordinates
1491 ('y', default) or cooked coordinates ('n')
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001493 mtrr_chunk_size=nn[KMG] [X86]
Matt LaPlante19f59462009-04-27 15:06:31 +02001494 used for mtrr cleanup. It is largest continuous chunk
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001495 that could hold holes aka. UC entries.
1496
1497 mtrr_gran_size=nn[KMG] [X86]
1498 Used for mtrr cleanup. It is granularity of mtrr block.
1499 Default is 1.
1500 Large value could prevent small alignment from
1501 using up MTRRs.
1502
1503 mtrr_spare_reg_nr=n [X86]
1504 Format: <integer>
1505 Range: 0,7 : spare reg number
1506 Default : 1
1507 Used for mtrr cleanup. It is spare mtrr entries number.
1508 Set to 2 or more if your graphical card needs more.
1509
Linus Torvalds1da177e2005-04-16 15:20:36 -07001510 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1511
1512 NCR_D700= [HW,SCSI]
1513 See header of drivers/scsi/NCR_D700.c.
1514
1515 ncr5380= [HW,SCSI]
1516
1517 ncr53c400= [HW,SCSI]
1518
1519 ncr53c400a= [HW,SCSI]
1520
1521 ncr53c406a= [HW,SCSI]
1522
1523 ncr53c8xx= [HW,SCSI]
1524
1525 netdev= [NET] Network devices parameters
1526 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1527 Note that mem_start is often overloaded to mean
1528 something different and driver-specific.
Randy Dunlapa9913042005-10-23 12:57:11 -07001529 This usage is only documented in each driver source
1530 file if at all.
1531
Krzysztof Piotr Oledzki58401572008-07-21 10:01:34 -07001532 nf_conntrack.acct=
1533 [NETFILTER] Enable connection tracking flow accounting
1534 0 to disable accounting
1535 1 to enable accounting
1536 Default value depends on CONFIG_NF_CT_ACCT that is
1537 going to be removed in 2.6.29.
1538
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539 nfsaddrs= [NFS]
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001540 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541
1542 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
J. Bruce Fields6ded55d2008-04-07 15:59:03 -04001543 See Documentation/filesystems/nfsroot.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544
Trond Myklebusta72b4422006-01-03 09:55:41 +01001545 nfs.callback_tcpport=
1546 [NFS] set the TCP port on which the NFSv4 callback
1547 channel should listen.
1548
Trond Myklebuste571cbf2009-08-19 18:12:27 -04001549 nfs.cache_getent=
1550 [NFS] sets the pathname to the program which is used
1551 to update the NFS client cache entries.
1552
1553 nfs.cache_getent_timeout=
1554 [NFS] sets the timeout after which an attempt to
1555 update a cache entry is deemed to have failed.
1556
Trond Myklebust58df0952006-01-03 09:55:57 +01001557 nfs.idmap_cache_timeout=
1558 [NFS] set the maximum lifetime for idmapper cache
1559 entries.
1560
Trond Myklebustf43bf0b2007-10-09 12:01:04 -04001561 nfs.enable_ino64=
1562 [NFS] enable 64-bit inode numbers.
1563 If zero, the NFS client will fake up a 32-bit inode
1564 number for the readdir() and stat() syscalls instead
1565 of returning the full 64-bit number.
1566 The default is to return 64-bit inode numbers.
1567
Paul Mundt1e1030d2009-09-01 17:38:32 +09001568 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
Haavard Skinnemoene7ba1762007-10-10 14:58:29 +02001569 when a NMI is triggered.
1570 Format: [state][,regs][,debounce][,die]
1571
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301572 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001573 Format: [panic,][num]
1574 Valid num: 0,1,2
1575 0 - turn nmi_watchdog off
1576 1 - use the IO-APIC timer for the NMI watchdog
1577 2 - use the local APIC for the NMI watchdog using
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001578 a performance counter. Note: This will use one
1579 performance counter and the local APIC's performance
1580 vector.
1581 When panic is specified, panic when an NMI watchdog
1582 timeout occurs.
1583 This is useful when you use a panic=... timeout and
1584 need the box quickly up again.
Cyrill Gorcunov5b9a0e12008-11-01 18:06:51 +03001585 Instead of 1 and 2 it is possible to use the following
1586 symbolic names: lapic and ioapic
1587 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588
Anton Vorontsovbff38772009-07-08 11:10:56 -07001589 netpoll.carrier_timeout=
1590 [NET] Specifies amount of time (in seconds) that
1591 netpoll should wait for a carrier. By default netpoll
1592 waits 4 seconds.
1593
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001594 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
Linus Torvalds1da177e2005-04-16 15:20:36 -07001595 emulation library even if a 387 maths coprocessor
1596 is present.
1597
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001598 no_console_suspend
1599 [HW] Never suspend the console
1600 Disable suspending of consoles during suspend and
1601 hibernate operations. Once disabled, debugging
1602 messages can reach various consoles while the rest
1603 of the system is being put to sleep (ie, while
1604 debugging driver suspend/resume hooks). This may
1605 not work reliably with all consoles, but is known
1606 to work with serial and VGA consoles.
1607
Christoph Lameterc1aee212007-05-31 00:40:47 -07001608 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1609 caches in the slab allocator. Saves per-node memory,
1610 but will impact performance.
Paul Menage3395ee02006-12-06 20:32:16 -08001611
Randy Dunlapa9913042005-10-23 12:57:11 -07001612 noalign [KNL,ARM]
1613
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614 noapic [SMP,APIC] Tells the kernel to not make use of any
1615 IOAPICs that may be present in the system.
1616
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 nobats [PPC] Do not use BATs for mapping kernel lowmem
1618 on "Classic" PPC cores.
1619
1620 nocache [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001621
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001622 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1623
Shailabh Nagar163ecdf2006-07-30 03:03:11 -07001624 nodelayacct [KNL] Disable per-task delay accounting
1625
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1627
Paul Mundt6902aa82008-09-21 17:14:42 +09001628 nodsp [SH] Disable hardware DSP at boot time.
1629
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301630 noefi [X86] Disable EFI runtime services support.
Huang, Ying8b2cb7a2008-01-30 13:32:11 +01001631
Linus Torvalds1da177e2005-04-16 15:20:36 -07001632 noexec [IA-64]
1633
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301634 noexec [X86]
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001635 On X86-32 available only on PAE configured kernels.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001636 noexec=on: enable non-executable mappings (default)
Jiri Slabyf5a1b192008-04-12 10:28:25 +02001637 noexec=off: disable non-executable mappings
1638
1639 noexec32 [X86-64]
1640 This affects only 32-bit executables.
1641 noexec32=on: enable non-executable mappings (default)
1642 read doesn't imply executable mappings
1643 noexec32=off: disable non-executable mappings
1644 read implies executable mappings
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645
Paul Mundt6902aa82008-09-21 17:14:42 +09001646 nofpu [SH] Disable hardware FPU at boot time.
1647
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001648 nofxsr [BUGS=X86-32] Disables x86 floating point extended
Chuck Ebbert4f886512006-03-23 02:59:34 -08001649 register save and restore. The kernel will only save
1650 legacy floating-point registers on task switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651
Suresh Siddha0c752a92009-05-22 12:17:45 -07001652 noxsave [BUGS=X86] Disables x86 extended register state save
1653 and restore using xsave. The kernel will fallback to
1654 enabling legacy floating-point and sse state.
1655
Paulius Zaleckas01a24d22009-03-31 13:55:44 +01001656 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1657 wfi(ARM) instruction doesn't work correctly and not to
1658 use it. This is also useful when using JTAG debugger.
Randy Dunlapa9913042005-10-23 12:57:11 -07001659
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001660 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661 instruction doesn't work correctly and not to
1662 use it.
1663
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -06001664 no_file_caps Tells the kernel not to honor file capabilities. The
1665 only way then for a file to be executed with privilege
1666 is to be setuid root or executed by root.
1667
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668 nohalt [IA-64] Tells the kernel not to use the power saving
1669 function PAL_HALT_LIGHT when idle. This increases
1670 power-consumption. On the positive side, it reduces
1671 interrupt wake-up latency, which may improve performance
1672 in certain environments such as networked servers or
1673 real-time systems.
1674
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001675 nohz= [KNL] Boottime enable/disable dynamic ticks
1676 Valid arguments: on, off
1677 Default: on
1678
Paul Mundteeee7852009-04-02 12:31:16 +09001679 noiotrap [SH] Disables trapped I/O port accesses.
1680
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001681 noirqdebug [X86-32] Disables the code which attempts to detect and
Linus Torvalds1da177e2005-04-16 15:20:36 -07001682 disable unhandled interrupt sources.
1683
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301684 no_timer_check [X86,APIC] Disables the code which tests for
Zachary Amsden8542b202006-12-07 02:14:09 +01001685 broken timer IRQ sources.
1686
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687 noisapnp [ISAPNP] Disables ISA PnP code.
1688
1689 noinitrd [RAM] Tells the kernel not to load any configured
1690 initial RAM disk.
1691
Weidong Han03ea8152009-04-17 16:42:15 +08001692 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1693 remapping.
1694
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695 nointroute [IA-64]
1696
Tony Luck0aa366f2007-07-20 11:22:30 -07001697 nojitter [IA64] Disables jitter checking for ITC timers.
1698
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001699 nolapic [X86-32,APIC] Do not enable or use the local APIC.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001700
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001701 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
Thomas Gleixnerad62ca22007-03-22 00:11:21 -08001702
Linus Torvalds1da177e2005-04-16 15:20:36 -07001703 noltlbs [PPC] Do not use large page/tlb entries for kernel
1704 lowmem mapping on PPC40x.
1705
Horms312f1f02006-02-22 09:57:55 +09001706 nomca [IA-64] Disable machine check abort handling
1707
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001708 nomce [X86-32] Machine Check Exception
Hormsabe37e52006-04-01 01:36:09 +02001709
Andres Salomon83d73842007-10-12 23:04:06 +02001710 nomfgpt [X86-32] Disable Multi-Function General Purpose
1711 Timer usage (for AMD Geode machines).
1712
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001713 norandmaps Don't use address space randomization. Equivalent to
1714 echo 0 > /proc/sys/kernel/randomize_va_space
1715
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001716 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
Jeremy Fitzhardinge959b4fd2007-05-02 19:27:16 +02001717
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001718 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02001719 with UP alternatives
1720
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721 noresidual [PPC] Don't use residual data on PReP machines.
1722
Randy Dunlapa9913042005-10-23 12:57:11 -07001723 noresume [SWSUSP] Disables resume and restores original swap
1724 space.
1725
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726 no-scroll [VGA] Disables scrollback.
1727 This is required for the Braillex ib80-piezo Braille
1728 reader made by F.H. Papenmeier (Germany).
1729
1730 nosbagart [IA-64]
1731
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001732 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
Chuck Ebbert4f886512006-03-23 02:59:34 -08001733
Len Brown61ec7562007-08-16 03:34:22 -04001734 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1735 and disable the IO APIC. legacy for "maxcpus=0".
Linus Torvalds1da177e2005-04-16 15:20:36 -07001736
Dave Jones97842212007-07-15 23:41:05 -07001737 nosoftlockup [KNL] Disable the soft-lockup detector.
1738
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001739 noswapaccount [KNL] Disable accounting of swap in memory resource
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01001740 controller. (See Documentation/cgroups/memory.txt)
KAMEZAWA Hiroyukic0777192009-01-07 18:07:57 -08001741
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 nosync [HW,M68K] Disables sync negotiation for all devices.
1743
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001744 notsc [BUGS=X86-32] Disable Time Stamp Counter
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745
1746 nousb [USB] Disable the USB subsystem
1747
1748 nowb [ARM]
Randy Dunlapa9913042005-10-23 12:57:11 -07001749
Weidong Han2b2fd872009-04-17 16:42:12 +08001750 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1751
Fenghua Yua6c75b862008-03-14 13:57:08 -07001752 nptcg= [IA64] Override max number of concurrent global TLB
1753 purges which is reported from either PAL_VM_SUMMARY or
1754 SAL PALO.
1755
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07001756 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1757
KAMEZAWA Hiroyukif0c0b2b2007-07-15 23:38:01 -07001758 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1759 one of ['zone', 'node', 'default'] can be specified
1760 This can be set from sysctl after boot.
1761 See Documentation/sysctl/vm.txt for details.
1762
Randy Dunlap7c4be252009-01-06 14:42:44 -08001763 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1764 See Documentation/debugging-via-ohci1394.txt for more
1765 info.
1766
Andres Salomon3ef0e1f2008-04-29 00:59:53 -07001767 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1768 Rather than timing out after 20 ms if an EC
1769 command is not properly ACKed, override the length
1770 of the timeout. We have interrupts disabled while
1771 waiting for the ACK, so if this is set too high
1772 interrupts *may* be lost!
1773
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774 opl3= [HW,OSS]
1775 Format: <io>
1776
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777 oprofile.timer= [HW]
1778 Use timer interrupt instead of performance counters
1779
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001780 oprofile.cpu_type= Force an oprofile cpu type
1781 This might be useful if you have an older oprofile
1782 userland or if you want common events.
Robert Richter8d7ff4f2009-06-23 11:48:14 +02001783 Format: { arch_perfmon }
1784 arch_perfmon: [X86] Force use of architectural
Robert Richter7e4e0bd2009-05-06 12:10:23 +02001785 perfmon on Intel CPUs instead of the
1786 CPU specific event set.
Andi Kleen1dcdb5a2009-04-27 17:44:11 +02001787
Linus Torvalds1da177e2005-04-16 15:20:36 -07001788 osst= [HW,SCSI] SCSI Tape Driver
1789 Format: <buffer_size>,<write_threshold>
1790 See also Documentation/scsi/st.txt.
1791
1792 panic= [KNL] Kernel behaviour on panic
1793 Format: <timeout>
1794
1795 parkbd.port= [HW] Parallel port number the keyboard adapter is
1796 connected to, default is 0.
1797 Format: <parport#>
1798 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1799 0 for XT, 1 for AT (default is AT).
Randy Dunlapa9913042005-10-23 12:57:11 -07001800 Format: <mode>
Linus Torvalds1da177e2005-04-16 15:20:36 -07001801
Randy Dunlapa9913042005-10-23 12:57:11 -07001802 parport= [HW,PPT] Specify parallel ports. 0 disables.
1803 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1804 Use 'auto' to force the driver to use any
1805 IRQ/DMA settings detected (the default is to
1806 ignore detected IRQ/DMA settings because of
1807 possible conflicts). You can specify the base
1808 address, IRQ, and DMA settings; IRQ and DMA
1809 should be numbers, or 'auto' (for using detected
1810 settings on that particular port), or 'nofifo'
1811 (to avoid using a FIFO even if it is detected).
1812 Parallel ports are assigned in the order they
1813 are specified on the command line, starting
1814 with parport0.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815
Randy Dunlapa9913042005-10-23 12:57:11 -07001816 parport_init_mode= [HW,PPT]
1817 Configure VIA parallel port to operate in
1818 a specific mode. This is necessary on Pegasos
1819 computer where firmware has no options for setting
1820 up parallel port mode and sets it to spp.
1821 Currently this function knows 686a and 8231 chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001822 Format: [spp|ps2|epp|ecp|ecpepp]
1823
Randy Dunlapa9913042005-10-23 12:57:11 -07001824 pas2= [HW,OSS] Format:
1825 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1826
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827 pas16= [HW,SCSI]
1828 See header of drivers/scsi/pas16.c.
1829
Andrew Mortondd287792006-03-23 03:00:57 -08001830 pause_on_oops=
1831 Halt all CPUs after the first oops has been printed for
1832 the specified number of seconds. This is to be used if
1833 your oopses keep scrolling off the screen.
1834
Linus Torvalds1da177e2005-04-16 15:20:36 -07001835 pcbit= [HW,ISDN]
1836
1837 pcd. [PARIDE]
1838 See header of drivers/block/paride/pcd.c.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001839 See also Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001840
Randy Dunlapa9913042005-10-23 12:57:11 -07001841 pci=option[,option...] [PCI] various PCI subsystem options:
Bjorn Helgaas1cc0ca22009-01-14 10:04:36 -07001842 earlydump [X86] dump PCI config space before the kernel
1843 changes anything
Andi Kleenc0115602008-08-22 09:53:39 +02001844 off [X86] don't probe for the PCI bus
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001845 bios [X86-32] force use of PCI BIOS, don't access
Randy Dunlapa9913042005-10-23 12:57:11 -07001846 the hardware directly. Use this if your machine
1847 has a non-standard PCI host bridge.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001848 nobios [X86-32] disallow use of PCI BIOS, only direct
Randy Dunlapa9913042005-10-23 12:57:11 -07001849 hardware access methods are allowed. Use this
1850 if you experience crashes upon bootup and you
1851 suspect they are caused by the BIOS.
Andi Kleenc0115602008-08-22 09:53:39 +02001852 conf1 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001853 Mechanism 1.
Andi Kleenc0115602008-08-22 09:53:39 +02001854 conf2 [X86] Force use of PCI Configuration
Randy Dunlapa9913042005-10-23 12:57:11 -07001855 Mechanism 2.
Randy Dunlap7f785762007-10-05 13:17:58 -07001856 noaer [PCIE] If the PCIEAER kernel config parameter is
1857 enabled, this kernel boot option can be used to
1858 disable the use of PCIE advanced error reporting.
Jeff Garzik32a2eea2007-10-11 16:57:27 -04001859 nodomains [PCI] Disable support for multiple PCI
1860 root domains (aka PCI segments, in ACPI-speak).
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05301861 nommconf [X86] Disable use of MMCONFIG for PCI
Bjorn Helgaas61be6d62006-02-15 15:17:43 -08001862 Configuration
Andreas Herrmann12983072009-06-07 16:15:16 +02001863 check_enable_amd_mmconf [X86] check for and enable
1864 properly configured MMIO access to PCI
1865 config space on AMD family 10h CPU
Matthew Wilcox309e57d2006-03-05 22:33:34 -07001866 nomsi [MSI] If the PCI_MSI kernel config parameter is
1867 enabled, this kernel boot option can be used to
1868 disable the use of MSI interrupts system-wide.
Stefan Assmanna9322f62008-06-11 16:35:14 +02001869 noioapicquirk [APIC] Disable all boot interrupt quirks.
1870 Safety option to keep boot IRQs enabled. This
1871 should never be necessary.
Stefan Assmann91979792008-06-11 16:35:15 +02001872 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1873 primary IO-APIC for bridges that cannot disable
1874 boot IRQs. This fixes a source of spurious IRQs
1875 when the system masks IRQs.
Stefan Assmann41b9eb22008-07-15 13:48:55 +02001876 noioapicreroute [APIC] Disable workaround that uses the
1877 boot IRQ equivalent of an IRQ that connects to
1878 a chipset where boot IRQs cannot be disabled.
1879 The opposite of ioapicreroute.
Alan Coxcd4f0ef2007-07-31 00:37:59 -07001880 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
Randy Dunlapa9913042005-10-23 12:57:11 -07001881 routing table. These calls are known to be buggy
1882 on several machines and they hang the machine
1883 when used, but on other computers it's the only
1884 way to get the interrupt routing table. Try
1885 this option if the kernel is unable to allocate
1886 IRQs or discover secondary PCI buses on your
1887 motherboard.
Andi Kleenc0115602008-08-22 09:53:39 +02001888 rom [X86] Assign address space to expansion ROMs.
Randy Dunlapa9913042005-10-23 12:57:11 -07001889 Use with caution as certain devices share
1890 address decoders between ROMs and other
1891 resources.
Andi Kleenc0115602008-08-22 09:53:39 +02001892 norom [X86] Do not assign address space to
Gary Hadebb71ad82008-05-12 13:57:46 -07001893 expansion ROMs that do not already have
1894 BIOS assigned address ranges.
Andi Kleenc0115602008-08-22 09:53:39 +02001895 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
Randy Dunlapa9913042005-10-23 12:57:11 -07001896 assigned automatically to PCI devices. You can
1897 make the kernel exclude IRQs of your ISA cards
1898 this way.
Andi Kleenc0115602008-08-22 09:53:39 +02001899 pirqaddr=0xAAAAA [X86] Specify the physical address
Randy Dunlapa9913042005-10-23 12:57:11 -07001900 of the PIRQ table (normally generated
1901 by the BIOS) if it is outside the
1902 F0000h-100000h range.
Andi Kleenc0115602008-08-22 09:53:39 +02001903 lastbus=N [X86] Scan all buses thru bus #N. Can be
Randy Dunlapa9913042005-10-23 12:57:11 -07001904 useful if the kernel is unable to find your
1905 secondary buses and you want to tell it
1906 explicitly which ones they are.
Andi Kleenc0115602008-08-22 09:53:39 +02001907 assign-busses [X86] Always assign all PCI bus
Randy Dunlapa9913042005-10-23 12:57:11 -07001908 numbers ourselves, overriding
1909 whatever the firmware may have done.
Andi Kleenc0115602008-08-22 09:53:39 +02001910 usepirqmask [X86] Honor the possible IRQ mask stored
Randy Dunlapa9913042005-10-23 12:57:11 -07001911 in the BIOS $PIR table. This is needed on
1912 some systems with broken BIOSes, notably
1913 some HP Pavilion N5400 and Omnibook XE3
1914 notebooks. This will have no effect if ACPI
1915 IRQ routing is enabled.
Andi Kleenc0115602008-08-22 09:53:39 +02001916 noacpi [X86] Do not use ACPI for IRQ routing
Randy Dunlapa9913042005-10-23 12:57:11 -07001917 or for PCI scanning.
Linus Torvalds236e9462009-06-24 16:23:03 -07001918 use_crs [X86] Use _CRS for PCI resource
Gary Hade62f420f2007-10-03 15:56:51 -07001919 allocation.
Randy Dunlapa9913042005-10-23 12:57:11 -07001920 routeirq Do IRQ routing for all PCI devices.
1921 This is normally done in pci_enable_device(),
1922 so this option is a temporary workaround
1923 for broken drivers that don't call it.
Yinghai Lu13a6ddb2008-03-27 01:31:18 -07001924 skip_isa_align [X86] do not align io start addr, so can
1925 handle more pci cards
Randy Dunlapa9913042005-10-23 12:57:11 -07001926 firmware [ARM] Do not re-enumerate the bus but instead
1927 just use the configuration from the
1928 bootloader. This is currently used on
1929 IXP2000 systems where the bus has to be
1930 configured a certain way for adjunct CPUs.
Andi Kleen0637a702006-09-26 10:52:41 +02001931 noearly [X86] Don't do any early type 1 scanning.
1932 This might help on some broken boards which
1933 machine check when some devices' config space
1934 is read. But various workarounds are disabled
1935 and some IOMMU drivers will not work.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001936 bfsort Sort PCI devices into breadth-first order.
1937 This sorting is done to get a device
1938 order compatible with older (<= 2.4) kernels.
1939 nobfsort Don't sort PCI devices into breadth-first order.
Atsushi Nemoto4516a612007-02-05 16:36:06 -08001940 cbiosize=nn[KMG] The fixed amount of bus space which is
1941 reserved for the CardBus bridge's IO window.
1942 The default value is 256 bytes.
1943 cbmemsize=nn[KMG] The fixed amount of bus space which is
1944 reserved for the CardBus bridge's memory
1945 window. The default value is 64 megabytes.
Yuji Shimada32a9a682009-03-16 17:13:39 +09001946 resource_alignment=
1947 Format:
1948 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1949 Specifies alignment and device to reassign
1950 aligned memory resources.
1951 If <order of align> is not specified,
1952 PAGE_SIZE is used as alignment.
1953 PCI-PCI bridge can be specified, if resource
1954 windows need to be expanded.
Andrew Patterson43c16402009-04-22 16:52:09 -06001955 ecrc= Enable/disable PCIe ECRC (transaction layer
1956 end-to-end CRC checking).
1957 bios: Use BIOS/firmware settings. This is the
1958 the default.
1959 off: Turn ECRC off
1960 on: Turn ECRC on.
Matt Domsch6b4b78f2006-09-29 15:23:23 -05001961
Chuck Ebberte5665a42008-09-24 20:40:34 -04001962 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1963 Management.
1964 off Disable ASPM.
1965 force Enable ASPM even on devices that claim not to support it.
1966 WARNING: Forcing ASPM on may cause system lockups.
1967
Linus Torvalds1da177e2005-04-16 15:20:36 -07001968 pcmv= [HW,PCMCIA] BadgePAD 4
1969
1970 pd. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001971 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001972
1973 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1974 boot time.
1975 Format: { 0 | 1 }
1976 See arch/parisc/kernel/pdc_chassis.c
1977
Tejun Heof58dc012009-08-14 15:00:50 +09001978 percpu_alloc= Select which percpu first chunk allocator to use.
Tejun Heoe933a732009-08-14 15:00:53 +09001979 Currently supported values are "embed" and "page".
1980 Archs may support subset or none of the selections.
1981 See comments in mm/percpu.c for details on each
1982 allocator. This parameter is primarily for debugging
1983 and performance comparison.
Tejun Heofa8a7092009-06-22 11:56:24 +09001984
Linus Torvalds1da177e2005-04-16 15:20:36 -07001985 pf. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001986 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001987
1988 pg. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00001989 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990
1991 pirq= [SMP,APIC] Manual mp-table setup
Uwe Hermann71cced62008-10-20 09:32:21 -07001992 See Documentation/x86/i386/IO-APIC.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001993
1994 plip= [PPT,NET] Parallel port network link
1995 Format: { parport<nr> | timid | 0 }
1996 See also Documentation/parport.txt.
1997
Thomas Gleixnerde32a242008-07-12 05:33:30 +02001998 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1999 Override pmtimer IOPort with a hex value.
2000 e.g. pmtmr=0x508
2001
Bjorn Helgaas97ef0622008-08-19 16:53:41 -06002002 pnp.debug [PNP]
2003 Enable PNP debug messages. This depends on the
2004 CONFIG_PNP_DEBUG_MESSAGES option.
2005
Linus Torvalds1da177e2005-04-16 15:20:36 -07002006 pnpacpi= [ACPI]
2007 { off }
2008
2009 pnpbios= [ISAPNP]
2010 { on | off | curr | res | no-curr | no-res }
2011
2012 pnp_reserve_irq=
2013 [ISAPNP] Exclude IRQs for the autoconfiguration
2014
2015 pnp_reserve_dma=
2016 [ISAPNP] Exclude DMAs for the autoconfiguration
2017
2018 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
Randy Dunlapa9913042005-10-23 12:57:11 -07002019 Ranges are in pairs (I/O port base and size).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002020
2021 pnp_reserve_mem=
Randy Dunlapa9913042005-10-23 12:57:11 -07002022 [ISAPNP] Exclude memory regions for the
2023 autoconfiguration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002024 Ranges are in pairs (memory base and size).
2025
Randy Dunlap4af94f32009-04-17 18:30:28 -07002026 ports= [IP_VS_FTP] IPVS ftp helper module
2027 Default is 21.
2028 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2029 may be specified.
2030 Format: <port>,<port>....
2031
Ingo Molnar45807a12007-07-15 23:40:10 -07002032 print-fatal-signals=
2033 [KNL] debug: print fatal signals
2034 print-fatal-signals=1: print segfault info to
2035 the kernel console.
2036 default: off.
2037
Randy Dunlape84845c2007-07-15 23:40:25 -07002038 printk.time= Show timing data prefixed to each printk message line
2039 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2040
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002041 processor.max_cstate= [HW,ACPI]
2042 Limit processor to maximum C-state
2043 max_cstate=9 overrides any DMI blacklist limit.
2044
2045 processor.nocst [HW,ACPI]
2046 Ignore the _CST method to determine C-states,
2047 instead using the legacy FADT method
2048
Linus Torvalds1da177e2005-04-16 15:20:36 -07002049 profile= [KNL] Enable kernel profiling via /proc/profile
Randy Dunlapa9913042005-10-23 12:57:11 -07002050 Format: [schedule,]<number>
2051 Param: "schedule" - profile schedule points.
2052 Param: <number> - step/bucket size as a power of 2 for
2053 statistical time based profiling.
Mel Gormanb3da2a72007-10-24 18:23:50 +02002054 Param: "sleep" - profile D-state sleeping (millisecs).
2055 Requires CONFIG_SCHEDSTATS
Dave Jonesc0fe2e62007-10-20 03:08:22 +02002056 Param: "kvm" - profile VM exits.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2059 before loading.
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002060 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002061
Randy Dunlapa9913042005-10-23 12:57:11 -07002062 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2063 probe for; one of (bare|imps|exps|lifebook|any).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002064 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2065 per second.
Randy Dunlapa9913042005-10-23 12:57:11 -07002066 psmouse.resetafter= [HW,MOUSE]
2067 Try to reset the device after so many bad packets
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068 (0 = never).
2069 psmouse.resolution=
2070 [HW,MOUSE] Set desired mouse resolution, in dpi.
2071 psmouse.smartscroll=
Randy Dunlapa9913042005-10-23 12:57:11 -07002072 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002073 0 = disabled, 1 = enabled (default).
2074
2075 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
Randy Dunlapa9913042005-10-23 12:57:11 -07002076 Format:
2077 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078
2079 pt. [PARIDE]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002080 See Documentation/blockdev/paride.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081
Kay Sieversdc8c8582007-08-15 12:25:38 +02002082 pty.legacy_count=
2083 [KNL] Number of legacy pty's. Overwrites compiled-in
2084 default number.
2085
Randy Dunlap7d2c5022006-09-29 02:01:02 -07002086 quiet [KNL] Disable most log messages
Randy Dunlapa9913042005-10-23 12:57:11 -07002087
Linus Torvalds1da177e2005-04-16 15:20:36 -07002088 r128= [HW,DRM]
2089
2090 raid= [HW,RAID]
2091 See Documentation/md.txt.
2092
Randy Dunlapa9913042005-10-23 12:57:11 -07002093 ramdisk_blocksize= [RAM]
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002094 See Documentation/blockdev/ramdisk.txt.
Randy Dunlapa9913042005-10-23 12:57:11 -07002095
Linus Torvalds1da177e2005-04-16 15:20:36 -07002096 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002097 See Documentation/blockdev/ramdisk.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002098
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002099 rcupdate.blimit= [KNL,BOOT]
2100 Set maximum number of finished RCU callbacks to process
2101 in one batch.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002102
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002103 rcupdate.qhimark= [KNL,BOOT]
2104 Set threshold of queued
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002105 RCU callbacks over which batch limiting is disabled.
2106
Robert P. J. Day24aaef82008-02-03 15:20:26 +02002107 rcupdate.qlowmark= [KNL,BOOT]
2108 Set threshold of queued RCU callbacks below which
2109 batch limiting is re-enabled.
Dipankar Sarma21a1ea92006-03-07 21:55:33 -08002110
Olof Johanssonffdfc402005-09-06 15:17:19 -07002111 rdinit= [KNL]
2112 Format: <full_path>
2113 Run specified binary instead of /init from the ramdisk,
2114 used for early userspace startup. See initrd.
2115
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002116 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002117 Format: <reboot_mode>[,<reboot_mode2>[,...]]
Randy Dunlapecb08d82009-01-06 14:42:44 -08002118 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07002119
Paul Jackson46b6d942008-07-04 10:00:09 -07002120 relax_domain_level=
2121 [KNL, SMP] Set scheduler's default relax_domain_level.
Thadeu Lima de Souza Cascardo21acb9c2009-02-04 10:12:08 +01002122 See Documentation/cgroups/cpusets.txt.
Paul Jackson46b6d942008-07-04 10:00:09 -07002123
Linus Torvalds1da177e2005-04-16 15:20:36 -07002124 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2125
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002126 reservetop= [X86-32]
Zachary Amsden461a9af2006-09-25 23:32:25 -07002127 Format: nn[KMG]
2128 Reserves a hole at the top of the kernel virtual
2129 address space.
2130
Vivek Goyal7e962872006-09-27 01:50:44 -07002131 reset_devices [KNL] Force drivers to reset the underlying device
2132 during initialization.
2133
Randy Dunlapa9913042005-10-23 12:57:11 -07002134 resume= [SWSUSP]
2135 Specify the partition device for software suspend
Linus Torvalds1da177e2005-04-16 15:20:36 -07002136
Rafael J. Wysockiecbd0da2006-12-06 20:34:13 -08002137 resume_offset= [SWSUSP]
2138 Specify the offset from the beginning of the partition
2139 given by "resume=" at which the swap header is located,
2140 in <PAGE_SIZE> units (needed only for swap files).
2141 See Documentation/power/swsusp-and-swap-files.txt
2142
Michael Neuling0a7b35c2007-02-10 01:44:33 -08002143 retain_initrd [RAM] Keep initrd memory after extraction
2144
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145 rhash_entries= [KNL,NET]
2146 Set number of hash buckets for route cache
2147
2148 riscom8= [HW,SERIAL]
2149 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2150
2151 ro [KNL] Mount root device read-only on boot
2152
2153 root= [KNL] Root filesystem
2154
2155 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2156 mount the root filesystem
2157
2158 rootflags= [KNL] Set root filesystem mount option string
2159
2160 rootfstype= [KNL] Set root filesystem type
2161
Pierre Ossmancc1ed752007-07-15 23:40:35 -07002162 rootwait [KNL] Wait (indefinitely) for root device to show up.
2163 Useful for devices that are detected asynchronously
2164 (e.g. USB and MMC devices).
2165
James Morris20510f22007-10-16 23:31:32 -07002166 root_plug.vendor_id=
2167 [ROOTPLUG] Override the default vendor ID
2168
2169 root_plug.product_id=
2170 [ROOTPLUG] Override the default product ID
2171
2172 root_plug.debug=
2173 [ROOTPLUG] Enable debugging output
2174
Linus Torvalds1da177e2005-04-16 15:20:36 -07002175 rw [KNL] Mount root device read-write on boot
2176
2177 S [KNL] Run init in single mode
2178
2179 sa1100ir [NET]
2180 See drivers/net/irda/sa1100_ir.c.
2181
Linus Torvalds1da177e2005-04-16 15:20:36 -07002182 sbni= [NET] Granch SBNI12 leased line adapter
Randy Dunlapa9913042005-10-23 12:57:11 -07002183
Linus Torvalds1da177e2005-04-16 15:20:36 -07002184 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2185 Format: <io>[,<timeout>[,<isapnp>]]
2186
2187 scsi_debug_*= [SCSI]
2188 See drivers/scsi/scsi_debug.c.
2189
2190 scsi_default_dev_flags=
2191 [SCSI] SCSI default device flags
2192 Format: <integer>
2193
2194 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2195 Format: <vendor>:<model>:<flags>
2196 (flags are integer value)
2197
Randy Dunlap6af66322007-11-14 16:52:25 -08002198 scsi_logging_level= [SCSI] a bit mask of logging levels
2199 See drivers/scsi/scsi_logging.h for bits. Also
2200 settable via sysctl at dev.scsi.logging_level
2201 (/proc/sys/dev/scsi/logging_level).
2202 There is also a nice 'scsi_logging_level' script in the
2203 S390-tools package, available for download at
2204 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
Linus Torvalds1da177e2005-04-16 15:20:36 -07002205
Matthew Wilcox3e082a92006-09-28 15:19:20 -06002206 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2207 discovered. async scans them in kernel threads,
2208 allowing boot to proceed. none ignores them, expecting
2209 user space to do the scan.
2210
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002211 security= [SECURITY] Choose a security module to enable at boot.
2212 If this boot parameter is not specified, only the first
2213 security module asking for security registration will be
2214 loaded. An invalid security module name will be treated
2215 as if no module has been chosen.
2216
2217 selinux= [SELINUX] Disable or enable SELinux at boot time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002218 Format: { "0" | "1" }
2219 See security/selinux/Kconfig help text.
2220 0 -- disable.
2221 1 -- enable.
2222 Default value is set via kernel config option.
2223 If enabled at boot time, /selinux/disable can be used
2224 later to disable prior to initial policy load.
2225
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002226 serialnumber [BUGS=X86-32]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002227
Linus Torvalds1da177e2005-04-16 15:20:36 -07002228 shapers= [NET]
2229 Maximal number of shapers.
Randy Dunlapa9913042005-10-23 12:57:11 -07002230
Yinghai Lub05f78f2008-08-22 01:32:50 -07002231 show_msr= [x86] show boot-time MSR settings
2232 Format: { <integer> }
2233 Show boot-time (BIOS-initialized) MSR settings.
2234 The parameter means the number of CPUs to show,
2235 for example 1 means boot CPU only.
2236
Linus Torvalds1da177e2005-04-16 15:20:36 -07002237 sim710= [SCSI,HW]
2238 See header of drivers/scsi/sim710.c.
2239
2240 simeth= [IA-64]
2241 simscsi=
Randy Dunlapa9913042005-10-23 12:57:11 -07002242
Linus Torvalds1da177e2005-04-16 15:20:36 -07002243 slram= [HW,MTD]
2244
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002245 slub_debug[=options[,slabs]] [MM, SLUB]
2246 Enabling slub_debug allows one to determine the
2247 culprit if slab objects become corrupted. Enabling
2248 slub_debug can create guard zones around objects and
2249 may poison objects when not in use. Also tracks the
2250 last alloc / free. For more information see
2251 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002252
2253 slub_max_order= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002254 Determines the maximum allowed order for slabs.
2255 A high setting may cause OOMs due to memory
2256 fragmentation. For more information see
2257 Documentation/vm/slub.txt.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002258
2259 slub_min_objects= [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002260 The minimum number of objects per slab. SLUB will
2261 increase the slab order up to slub_max_order to
2262 generate a sufficiently large slab able to contain
2263 the number of objects indicated. The higher the number
2264 of objects the smaller the overhead of tracking slabs
2265 and the less frequently locks need to be acquired.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002266 For more information see Documentation/vm/slub.txt.
2267
2268 slub_min_order= [MM, SLUB]
2269 Determines the mininum page order for slabs. Must be
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002270 lower than slub_max_order.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002271 For more information see Documentation/vm/slub.txt.
2272
2273 slub_nomerge [MM, SLUB]
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002274 Disable merging of slabs with similar size. May be
Christoph Lameterc1aee212007-05-31 00:40:47 -07002275 necessary if there is some reason to distinguish
Christoph Lameterf0630ff2007-07-15 23:38:14 -07002276 allocs to different slabs. Debug options disable
2277 merging on their own.
Christoph Lameterc1aee212007-05-31 00:40:47 -07002278 For more information see Documentation/vm/slub.txt.
2279
Linus Torvalds1da177e2005-04-16 15:20:36 -07002280 smart2= [HW]
2281 Format: <io1>[,<io2>[,...,<io8>]]
2282
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002283 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
Jeremy Fitzhardingeb7fb4af2007-05-02 19:27:13 +02002284 attempt to substitute SMP alternatives once at boot.
2285
Bjorn Helgaasd0d4f692007-05-08 00:36:05 -07002286 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2287 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2288 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2289 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2290 smsc-ircc2.ircc_irq= [HW] IRQ line
2291 smsc-ircc2.ircc_dma= [HW] DMA channel
2292 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2293 0: Toshiba Satellite 1800 (GP data pin select)
2294 1: Fast pin select (default)
2295 2: ATC IRMode
2296
Linus Torvalds1da177e2005-04-16 15:20:36 -07002297 snd-ad1816a= [HW,ALSA]
2298
2299 snd-ad1848= [HW,ALSA]
2300
2301 snd-ali5451= [HW,ALSA]
2302
2303 snd-als100= [HW,ALSA]
2304
2305 snd-als4000= [HW,ALSA]
2306
2307 snd-azt2320= [HW,ALSA]
2308
2309 snd-cmi8330= [HW,ALSA]
2310
2311 snd-cmipci= [HW,ALSA]
2312
2313 snd-cs4231= [HW,ALSA]
2314
2315 snd-cs4232= [HW,ALSA]
2316
2317 snd-cs4236= [HW,ALSA]
2318
2319 snd-cs4281= [HW,ALSA]
2320
2321 snd-cs46xx= [HW,ALSA]
2322
2323 snd-dt019x= [HW,ALSA]
2324
2325 snd-dummy= [HW,ALSA]
2326
2327 snd-emu10k1= [HW,ALSA]
2328
2329 snd-ens1370= [HW,ALSA]
2330
2331 snd-ens1371= [HW,ALSA]
2332
2333 snd-es968= [HW,ALSA]
2334
2335 snd-es1688= [HW,ALSA]
2336
2337 snd-es18xx= [HW,ALSA]
2338
2339 snd-es1938= [HW,ALSA]
2340
2341 snd-es1968= [HW,ALSA]
2342
2343 snd-fm801= [HW,ALSA]
2344
2345 snd-gusclassic= [HW,ALSA]
2346
2347 snd-gusextreme= [HW,ALSA]
2348
2349 snd-gusmax= [HW,ALSA]
2350
2351 snd-hdsp= [HW,ALSA]
2352
2353 snd-ice1712= [HW,ALSA]
2354
2355 snd-intel8x0= [HW,ALSA]
2356
2357 snd-interwave= [HW,ALSA]
2358
2359 snd-interwave-stb=
2360 [HW,ALSA]
2361
2362 snd-korg1212= [HW,ALSA]
2363
2364 snd-maestro3= [HW,ALSA]
2365
2366 snd-mpu401= [HW,ALSA]
2367
2368 snd-mtpav= [HW,ALSA]
2369
2370 snd-nm256= [HW,ALSA]
2371
2372 snd-opl3sa2= [HW,ALSA]
2373
2374 snd-opti92x-ad1848=
2375 [HW,ALSA]
2376
2377 snd-opti92x-cs4231=
2378 [HW,ALSA]
2379
2380 snd-opti93x= [HW,ALSA]
2381
2382 snd-pmac= [HW,ALSA]
2383
2384 snd-rme32= [HW,ALSA]
2385
2386 snd-rme96= [HW,ALSA]
2387
2388 snd-rme9652= [HW,ALSA]
2389
2390 snd-sb8= [HW,ALSA]
2391
2392 snd-sb16= [HW,ALSA]
2393
2394 snd-sbawe= [HW,ALSA]
2395
2396 snd-serial= [HW,ALSA]
2397
2398 snd-sgalaxy= [HW,ALSA]
2399
2400 snd-sonicvibes= [HW,ALSA]
2401
2402 snd-sun-amd7930=
2403 [HW,ALSA]
2404
2405 snd-sun-cs4231= [HW,ALSA]
2406
2407 snd-trident= [HW,ALSA]
2408
2409 snd-usb-audio= [HW,ALSA,USB]
2410
2411 snd-via82xx= [HW,ALSA]
2412
2413 snd-virmidi= [HW,ALSA]
2414
2415 snd-wavefront= [HW,ALSA]
2416
2417 snd-ymfpci= [HW,ALSA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002418
Ingo Molnar9c44bc02008-05-12 21:21:04 +02002419 softlockup_panic=
2420 [KNL] Should the soft-lockup detector generate panics.
2421
Linus Torvalds1da177e2005-04-16 15:20:36 -07002422 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2423 See Documentation/sonypi.txt
2424
2425 specialix= [HW,SERIAL] Specialix multi-serial port adapter
Randy Dunlap31c00fc2008-11-13 21:33:24 +00002426 See Documentation/serial/specialix.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427
2428 spia_io_base= [HW,MTD]
2429 spia_fio_base=
2430 spia_pedr=
2431 spia_peddr=
2432
2433 sscape= [HW,OSS]
2434 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
Randy Dunlapa9913042005-10-23 12:57:11 -07002435
Linus Torvalds1da177e2005-04-16 15:20:36 -07002436 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2437 See Documentation/scsi/st.txt.
2438
Steven Rostedtf38f1d22008-12-16 23:06:40 -05002439 stacktrace [FTRACE]
2440 Enabled the stack tracer on boot up.
2441
Linus Torvalds1da177e2005-04-16 15:20:36 -07002442 sti= [PARISC,HW]
2443 Format: <num>
2444 Set the STI (builtin display/keyboard on the HP-PARISC
2445 machines) console (graphic card) which should be used
2446 as the initial boot-console.
2447 See also comment in drivers/video/console/sticore.c.
2448
2449 sti_font= [HW]
2450 See comment in drivers/video/console/sticore.c.
2451
2452 stifb= [HW]
2453 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2454
Trond Myklebustcbf11072009-08-09 15:06:19 -04002455 sunrpc.min_resvport=
2456 sunrpc.max_resvport=
2457 [NFS,SUNRPC]
2458 SunRPC servers often require that client requests
2459 originate from a privileged port (i.e. a port in the
2460 range 0 < portnr < 1024).
2461 An administrator who wishes to reserve some of these
2462 ports for other uses may adjust the range that the
2463 kernel's sunrpc client considers to be privileged
2464 using these two parameters to set the minimum and
2465 maximum port values.
2466
Greg Banks42a7fc42007-03-06 01:42:23 -08002467 sunrpc.pool_mode=
2468 [NFS]
2469 Control how the NFS server code allocates CPUs to
2470 service thread pools. Depending on how many NICs
2471 you have and where their interrupts are bound, this
2472 option will affect which CPUs will do NFS serving.
2473 Note: this parameter cannot be changed while the
2474 NFS server is running.
2475
2476 auto the server chooses an appropriate mode
2477 automatically using heuristics
2478 global a single global pool contains all CPUs
2479 percpu one pool for each CPU
2480 pernode one pool for each NUMA node (equivalent
2481 to global on non-NUMA machines)
2482
Trond Myklebustcbf11072009-08-09 15:06:19 -04002483 sunrpc.tcp_slot_table_entries=
2484 sunrpc.udp_slot_table_entries=
2485 [NFS,SUNRPC]
2486 Sets the upper limit on the number of simultaneous
2487 RPC calls that can be sent from the client to a
2488 server. Increasing these values may allow you to
2489 improve throughput, but will also increase the
2490 amount of memory reserved for use by the client.
2491
Linus Torvalds1da177e2005-04-16 15:20:36 -07002492 swiotlb= [IA-64] Number of I/O TLB slabs
Randy Dunlapa9913042005-10-23 12:57:11 -07002493
Linus Torvalds1da177e2005-04-16 15:20:36 -07002494 switches= [HW,M68k]
2495
2496 sym53c416= [HW,SCSI]
2497 See header of drivers/scsi/sym53c416.c.
2498
Ingo Molnar5d6f6472006-12-13 00:34:36 -08002499 sysrq_always_enabled
2500 [KNL]
2501 Ignore sysrq setting - this boot parameter will
2502 neutralize any effect of /proc/sys/kernel/sysrq.
2503 Useful for debugging.
2504
Linus Torvalds1da177e2005-04-16 15:20:36 -07002505 t128= [HW,SCSI]
2506 See header of drivers/scsi/t128.c.
2507
2508 tdfx= [HW,DRM]
2509
David Brownell77437fd2008-07-23 21:28:33 -07002510 test_suspend= [SUSPEND]
2511 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2512 standby suspend) as the system sleep state to briefly
2513 enter during system startup. The system is woken from
2514 this state using a wakeup-capable RTC alarm.
2515
Linus Torvalds1da177e2005-04-16 15:20:36 -07002516 thash_entries= [KNL,NET]
2517 Set number of hash buckets for TCP connection
2518
Len Brownf8707ec2007-08-12 00:12:54 -04002519 thermal.act= [HW,ACPI]
2520 -1: disable all active trip points in all thermal zones
2521 <degrees C>: override all lowest active trip points
2522
Len Brownc52a7412007-08-14 15:49:32 -04002523 thermal.crt= [HW,ACPI]
2524 -1: disable all critical trip points in all thermal zones
Zhang Rui22a94d72008-10-17 02:41:20 -04002525 <degrees C>: override all critical trip points
Len Brownc52a7412007-08-14 15:49:32 -04002526
Len Brownf5487142007-08-12 00:12:44 -04002527 thermal.nocrt= [HW,ACPI]
2528 Set to disable actions on ACPI thermal zone
2529 critical and hot trip points.
2530
Len Brown72b33ef2007-08-12 00:12:17 -04002531 thermal.off= [HW,ACPI]
2532 1: disable ACPI thermal control
2533
Len Browna70cdc52007-08-12 00:12:35 -04002534 thermal.psv= [HW,ACPI]
2535 -1: disable all passive trip points
Randy Dunlapada9cfd2008-12-19 10:57:32 -08002536 <degrees C>: override all passive trip points to this
2537 value
Len Browna70cdc52007-08-12 00:12:35 -04002538
Len Brown730ff342007-08-12 00:12:26 -04002539 thermal.tzp= [HW,ACPI]
2540 Specify global default ACPI thermal zone polling rate
2541 <deci-seconds>: poll all this frequency
2542 0: no polling (default)
2543
Linus Torvalds1da177e2005-04-16 15:20:36 -07002544 tmscsim= [HW,SCSI]
2545 See comment before function dc390_setup() in
2546 drivers/scsi/tmscsim.c.
2547
Heiko Carstens2b1a61f2008-12-25 13:39:23 +01002548 topology= [S390]
2549 Format: {off | on}
2550 Specify if the kernel should make use of the cpu
2551 topology informations if the hardware supports these.
2552 The scheduler will make use of these informations and
2553 e.g. base its process migration decisions on it.
2554 Default is off.
2555
Linus Torvalds1da177e2005-04-16 15:20:36 -07002556 tp720= [HW,PS2]
2557
Li Zefan9d612be2009-06-24 17:33:15 +08002558 trace_buf_size=nn[KMG]
2559 [FTRACE] will set tracing buffer size.
KOSAKI Motohiro631595f2009-03-10 13:57:10 +09002560
Li Zefan020e5f82009-07-01 10:47:05 +08002561 trace_event=[event-list]
2562 [FTRACE] Set and start specified trace events in order
2563 to facilitate early boot debugging.
2564 See also Documentation/trace/events.txt
2565
Linus Torvalds1da177e2005-04-16 15:20:36 -07002566 trix= [HW,OSS] MediaTrix AudioTrix Pro
Randy Dunlapa9913042005-10-23 12:57:11 -07002567 Format:
2568 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2569
Alok Kataria395628e2008-10-24 17:22:01 -07002570 tsc= Disable clocksource-must-verify flag for TSC.
2571 Format: <string>
2572 [x86] reliable: mark tsc clocksource as reliable, this
2573 disables clocksource verification at runtime.
2574 Used to enable high-resolution timer mode on older
2575 hardware, and in virtualized environment.
2576
Randy Dunlapa9913042005-10-23 12:57:11 -07002577 turbografx.map[2|3]= [HW,JOY]
2578 TurboGraFX parallel port interface
2579 Format:
2580 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002581 See also Documentation/input/joystick-parport.txt
2582
2583 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2584 See header of drivers/scsi/u14-34f.c.
2585
2586 uart401= [HW,OSS]
2587 Format: <io>,<irq>
2588
2589 uart6850= [HW,OSS]
2590 Format: <io>,<irq>
2591
Alan Stern5f8364b2006-12-05 16:29:55 -05002592 uhci-hcd.ignore_oc=
2593 [USB] Ignore overcurrent events (default N).
2594 Some badly-designed motherboards generate lots of
2595 bogus events, for ports that aren't wired to
2596 anything. Set this parameter to avoid log spamming.
2597 Note that genuine overcurrent events won't be
2598 reported either.
2599
Simon Arlotte3a61b02008-07-19 23:32:54 +01002600 unknown_nmi_panic
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302601 [X86]
Simon Arlotte3a61b02008-07-19 23:32:54 +01002602 Set unknown_nmi_panic=1 early on boot.
2603
Alan Sternb5e795f2007-02-20 15:00:53 -05002604 usbcore.autosuspend=
2605 [USB] The autosuspend time delay (in seconds) used
2606 for newly-detected USB devices (default 2). This
2607 is the time required before an idle device will be
2608 autosuspended. Devices for which the delay is set
Alan Sterneaafbc32007-03-13 16:39:15 -04002609 to a negative value won't be autosuspended at all.
Alan Sternb5e795f2007-02-20 15:00:53 -05002610
Jaroslav Kyselafd7c5192008-10-10 16:24:45 +02002611 usbcore.usbfs_snoop=
2612 [USB] Set to log all usbfs traffic (default 0 = off).
2613
2614 usbcore.blinkenlights=
2615 [USB] Set to cycle leds on hubs (default 0 = off).
2616
2617 usbcore.old_scheme_first=
2618 [USB] Start with the old device initialization
2619 scheme (default 0 = off).
2620
2621 usbcore.use_both_schemes=
2622 [USB] Try the other device initialization scheme
2623 if the first one fails (default 1 = enabled).
2624
2625 usbcore.initial_descriptor_timeout=
2626 [USB] Specifies timeout for the initial 64-byte
2627 USB_REQ_GET_DESCRIPTOR request in milliseconds
2628 (default 5000 = 5.0 seconds).
2629
Linus Torvalds1da177e2005-04-16 15:20:36 -07002630 usbhid.mousepoll=
2631 [USBHID] The interval which mice are to be polled at.
Randy Dunlapa9913042005-10-23 12:57:11 -07002632
Alan Sternd4f373e2008-11-10 14:07:45 -05002633 usb-storage.delay_use=
2634 [UMS] The delay in seconds before a new device is
2635 scanned for Logical Units (default 5).
2636
2637 usb-storage.quirks=
2638 [UMS] A list of quirks entries to supplement or
2639 override the built-in unusual_devs list. List
2640 entries are separated by commas. Each entry has
2641 the form VID:PID:Flags where VID and PID are Vendor
2642 and Product ID values (4-digit hex numbers) and
2643 Flags is a set of characters, each corresponding
2644 to a common usb-storage quirk flag as follows:
Alan Sternc838ea42008-12-15 10:40:06 -05002645 a = SANE_SENSE (collect more than 18 bytes
2646 of sense data);
Alan Sternd4f373e2008-11-10 14:07:45 -05002647 c = FIX_CAPACITY (decrease the reported
2648 device capacity by one sector);
Alan Sternc838ea42008-12-15 10:40:06 -05002649 h = CAPACITY_HEURISTICS (decrease the
2650 reported device capacity by one
2651 sector if the number is odd);
Alan Sternd4f373e2008-11-10 14:07:45 -05002652 i = IGNORE_DEVICE (don't bind to this
2653 device);
2654 l = NOT_LOCKABLE (don't try to lock and
2655 unlock ejectable media);
2656 m = MAX_SECTORS_64 (don't transfer more
2657 than 64 sectors = 32 KB at a time);
Alan Sternc838ea42008-12-15 10:40:06 -05002658 o = CAPACITY_OK (accept the capacity
2659 reported by the device);
Alan Sternd4f373e2008-11-10 14:07:45 -05002660 r = IGNORE_RESIDUE (the device reports
2661 bogus residue values);
2662 s = SINGLE_LUN (the device has only one
2663 Logical Unit);
2664 w = NO_WP_DETECT (don't test whether the
2665 medium is write-protected).
2666 Example: quirks=0419:aaf5:rl,0421:0433:rc
2667
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302668 vdso= [X86,SH]
Jeremy Fitzhardinge1dbf5272007-05-02 19:27:12 +02002669 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
Ingo Molnare6e54942006-06-27 02:53:50 -07002670 vdso=1: enable VDSO (default)
2671 vdso=0: disable VDSO mapping
2672
Jaswinder Singh Rajput6cececf2009-04-14 14:03:43 +05302673 vdso32= [X86]
Roland McGrathaf65d642008-01-30 13:30:43 +01002674 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2675 vdso32=1: enable 32-bit VDSO (default)
2676 vdso32=0: disable 32-bit VDSO mapping
2677
Yasuaki Ishimatsud080d392007-07-17 21:22:55 +09002678 vector= [IA-64,SMP]
2679 vector=percpu: enable percpu vector domain
2680
Linus Torvalds1da177e2005-04-16 15:20:36 -07002681 video= [FB] Frame buffer configuration
2682 See Documentation/fb/modedb.txt.
2683
Alan Coxcd4f0ef2007-07-31 00:37:59 -07002684 vga= [BOOT,X86-32] Select a particular video mode
Kyle McMartin954a8b82009-02-19 16:48:14 -05002685 See Documentation/x86/boot.txt and
Randy Dunlapa9913042005-10-23 12:57:11 -07002686 Documentation/svga.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002687 Use vga=ask for menu.
2688 This is actually a boot loader parameter; the value is
2689 passed to the kernel using a special protocol.
2690
Randy Dunlapa9913042005-10-23 12:57:11 -07002691 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
Linus Torvalds1da177e2005-04-16 15:20:36 -07002692 size of <nn>. This can be used to increase the
2693 minimum size (128MB on x86). It can also be used to
2694 decrease the size and leave more room for directly
2695 mapped kernel RAM.
2696
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002697 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2698 Format: <command>
Linus Torvalds1da177e2005-04-16 15:20:36 -07002699
Peter Oberparleiter585c3042006-06-29 15:08:25 +02002700 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2701 Format: <command>
2702
2703 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2704 Format: <command>
Randy Dunlapa9913042005-10-23 12:57:11 -07002705
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002706 vt.default_blu= [VT]
2707 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2708 Change the default blue palette of the console.
2709 This is a 16-member array composed of values
2710 ranging from 0-255.
2711
2712 vt.default_grn= [VT]
2713 Format: <green0>,<green1>,<green2>,...,<green15>
2714 Change the default green palette of the console.
2715 This is a 16-member array composed of values
2716 ranging from 0-255.
2717
2718 vt.default_red= [VT]
2719 Format: <red0>,<red1>,<red2>,...,<red15>
2720 Change the default red palette of the console.
2721 This is a 16-member array composed of values
2722 ranging from 0-255.
2723
2724 vt.default_utf8=
2725 [VT]
2726 Format=<0|1>
2727 Set system-wide default UTF-8 mode for all tty's.
2728 Default is 1, i.e. UTF-8 mode is enabled for all
2729 newly opened terminals.
2730
Linus Torvalds1da177e2005-04-16 15:20:36 -07002731 waveartist= [HW,OSS]
2732 Format: <io>,<irq>,<dma>,<dma2>
Randy Dunlapa9913042005-10-23 12:57:11 -07002733
Linus Torvalds1da177e2005-04-16 15:20:36 -07002734 wd33c93= [HW,SCSI]
2735 See header of drivers/scsi/wd33c93.c.
2736
2737 wd7000= [HW,SCSI]
2738 See header of drivers/scsi/wd7000.c.
2739
2740 wdt= [WDT] Watchdog
Gabriel C8dfe9c22007-08-10 13:01:00 -07002741 See Documentation/watchdog/wdt.txt.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002742
Randy Dunlap0cb55ad2009-04-05 15:55:22 -07002743 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2744 default x2apic cluster mode on platforms
2745 supporting x2apic.
2746
Linus Torvalds1da177e2005-04-16 15:20:36 -07002747 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2748 xd_geo= See header of drivers/block/xd.c.
2749
2750 xirc2ps_cs= [NET,PCMCIA]
Randy Dunlapa9913042005-10-23 12:57:11 -07002751 Format:
2752 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
Linus Torvalds1da177e2005-04-16 15:20:36 -07002753
Randy Dunlapa9913042005-10-23 12:57:11 -07002754______________________________________________________________________
Linus Torvalds1da177e2005-04-16 15:20:36 -07002755
2756TODO:
2757
2758 Add documentation for ALSA options.
2759 Add more DRM drivers.